Editing Intramuscular injection

{{Short description|Medical injection into a muscle}}
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{{Infobox medical intervention
| Name        = Intramuscular injection
| Image       = Bracing for a short, sharp jab.jpg
| alt         =
| Caption     = A healthcare worker preparing to administer a vaccine via intramuscular injection
| MeshID      = D007273
| ICD9        = 99.1
| ICD10       = 3E023
| CPT         = 96372
}}

'''Intramuscular injection''', often abbreviated '''IM''', is the [[medical injection|injection]] of a substance into a [[muscle]]. In [[medicine]], it is one of several methods for [[parenteral|parenteral administration]] of medications. Intramuscular injection may be preferred because muscles have larger and more numerous [[blood vessel]]s than subcutaneous tissue, leading to faster absorption than [[subcutaneous injection|subcutaneous]] or [[intradermal injection]]s. Medication administered via intramuscular injection is not subject to the [[first-pass metabolism]] effect which affects oral medications.

Common sites for intramuscular injections include the [[deltoid muscle]] of the upper arm and the [[gluteal muscle]] of the buttock. In infants, the [[vastus lateralis muscle]] of the thigh is commonly used. The injection site must be cleaned before administering the injection, and the injection is then administered in a fast, darting motion to decrease the discomfort to the individual. The volume to be injected in the muscle is usually limited to 2–5 [[milliliter]]s, depending on injection site. A site with signs of infection or muscle atrophy should not be chosen. Intramuscular injections should not be used in people with [[myopathy|myopathies]] or those with trouble clotting.

Intramuscular injections commonly result in pain, redness, and swelling or [[inflammation]] around the injection site. These side effects are generally mild and last no more than a few days at most. Rarely, [[nerve]]s or blood vessels around the injection site can be damaged, resulting in severe pain or [[paralysis]]. If proper technique is not followed, intramuscular injections can result in localized infections such as [[abscess]]es and [[gangrene]]. While historically aspiration, or pulling back on the syringe before injection, was recommended to prevent inadvertent administration into a vein, it is no longer recommended for most injection sites by some countries.

==Uses==
Intramuscular injection is commonly used for medication administration. Medication administered in the muscle is generally quickly absorbed in the bloodstream, and avoids the [[first pass metabolism]] which occurs with oral administration.<ref>{{Citation|last=Saxen|first=Mark A.|title=Chapter 17 – Pharmacologic Management of Patient Behavior|date=2016-01-01|url=http://www.sciencedirect.com/science/article/pii/B978032328745600017X|work=McDonald and Avery's Dentistry for the Child and Adolescent (Tenth Edition)|pages=303–327|editor-last=Dean|editor-first=Jeffrey A.|place=St. Louis|publisher=Mosby|language=en|doi=10.1016/b978-0-323-28745-6.00017-x|isbn=978-0-323-28745-6|access-date=2020-11-25|url-access=subscription}}</ref> The medication may not be considered 100% [[bioavailability|bioavailable]] as it must still be absorbed from the muscle, which occurs over time.<ref name="Clin pharm">{{cite book |last1=Spruill |first1=William |last2=Wade |first2=William |last3=DiPiro |first3=Joseph T. |last4=Blouin |first4=Robert A. |last5=Pruemer |first5=Jane M. |title=Concepts in clinical pharmacokinetics |date=5 March 2014 |publisher=American Society of Health-System Pharmacists |location=Bethesda, MD |isbn=978-1-58528-387-3 |edition=Sixth}}</ref>{{rp|102–103}} An intramuscular injection is less invasive than an intravenous injection and also generally takes less time, as the site of injection (a muscle versus a vein) is much larger. Medications administered in the muscle may also be administered as [[depot injection]]s, which provide slow, continuous release of medicine over a longer period of time.<ref name=Wright>{{cite book |last1=Wright |first1=Jeremy C. |last2=Burgess |first2=Diane J. |title=Long acting injections and implants |date=29 January 2012 |publisher=Springer |isbn=978-1-4614-0554-2 |page=114}}</ref> Certain substances, including [[ketamine]], may be injected intramuscularly for [[recreational drug use|recreational]] purposes.<ref>{{cite journal |last1=Lankenau |first1=SE |last2=Clatts |first2=MC |title=Drug injection practices among high-risk youths: the first shot of ketamine. |journal=Journal of Urban Health: Bulletin of the New York Academy of Medicine |date=June 2004 |volume=81 |issue=2 |pages=232–48 |doi=10.1093/jurban/jth110 |pmid=15136657|pmc=1852476 }}</ref> Disadvantages of intramuscular administration include skill and technique required, pain from injection, anxiety or fear (especially in children), and difficulty in self-administration which limits its use in [[Outpatient clinic (hospital department)|outpatient medicine]].<ref name=Polania />

[[Vaccine]]s, especially [[inactivated vaccine]]s, are commonly administered via intramuscular injection.<ref name="Nurs2015">{{cite journal |last1=Sisson |first1=Helen |title=Aspirating during the intramuscular injection procedure: a systematic literature review |journal=Journal of Clinical Nursing |date=September 2015 |volume=24 |issue=17–18 |pages=2368–2375 |doi=10.1111/jocn.12824|pmid=25871949 |url=https://hull-repository.worktribe.com/373009/1/Article.pdf }}</ref> However, it has been estimated that for every vaccine injected intramuscularly, 20 injections are given to administer drugs or other therapy.<ref name="Nurs2015" /> This can include medications such as [[antibiotic]]s, [[immunoglobulin]], and [[hormone]]s such as testosterone and [[medroxyprogesterone]].<ref name="Polania">{{cite journal |vauthors=Polania Gutierrez JJ, Munakomi S |title=Intramuscular Injection |date=January 2020 |journal=StatPearls [Internet] |pmid=32310581 |url=https://www.ncbi.nlm.nih.gov/books/NBK556121/}}</ref> In a case of severe allergic reaction, or [[anaphylaxis]], a person may use an [[epinephrine (medication)|epinephrine]] [[autoinjector]] to self-administer epinephrine into the muscle.<ref>{{cite web|last=Mylan Specialty L.P.|title=EPIPEN®- epinephrine injection, EPIPEN Jr®- epinephrine injection|url=https://www.accessdata.fda.gov/drugsatfda_docs/label/2012/019430s053lbl.pdf|publisher=FDA Product Label|access-date=22 January 2014|url-status=live|archive-url=https://web.archive.org/web/20140201150929/http://www.accessdata.fda.gov/drugsatfda_docs/label/2012/019430s053lbl.pdf|archive-date=1 February 2014}}</ref>

==Contraindications==
Because an intramuscular injection can be used to administer many types of medications, specific [[contraindication]]s depend in large part on the medication being administered.<ref name=Nursing2002>{{cite journal |last1=Nicoll |first1=Leslie H. |last2=Hesby |first2=Amy |title=Intramuscular injection: An integrative research review and guideline for evidence-based practice |journal=Applied Nursing Research |date=August 2002 |volume=15 |issue=3 |pages=149–162 |doi=10.1053/apnr.2002.34142|pmid=12173166 }}</ref> Injections of medications are necessarily more invasive than other forms of administration such as by mouth or topical and require training to perform appropriately, without which complications can arise regardless of the medication being administered. For this reason, unless there are desired differences in rate of absorption, time to onset, or other pharmacokinetic parameters in the specific situation, a less invasive form of drug administration (usually by mouth) is preferred.<ref name=Nursing2002 />

Intramuscular injections are generally avoided in people with [[thrombocytopenia|low platelet count]] or clotting problems, to prevent harm due to potential damage to blood vessels during the injection. They are also not recommended in people who are in [[hypovolemic shock]], or have myopathy or [[muscle atrophy]], as these conditions may alter the absorption of the medication.<ref name="Polania" /> The damage to the muscle caused by an intramuscular injections may interfere with the accuracy of certain cardiac tests for people with suspected [[myocardial infarction]] and for this reason other methods of administration are preferred in such instances.<ref name="Polania" /> In people with an active myocardial infarction, the decrease in circulation may result in slower absorption from an IM injection.<ref name=LippNurs7 />{{rp|368–369}} Specific sites of administration may also be contraindicated if the desired injection site has an infection, swelling, or inflammation.<ref name="LippNurs7">{{cite book |editor1-last=Eckman |editor1-first=Margaret |title=Lippincott Nursing Procedures |date=October 9, 2015 |publisher=Lippincott Williams & Wilkins |location=Philadelphia |isbn=978-1-4698-5303-1 |edition=Seventh}}</ref>{{rp|368–369}} Within a specific site of administration, the injection should not be given directly over irritation or redness, birthmarks or moles, or areas with scar tissue.<ref name=LippNurs7 />{{rp|368–369}}

==Risks and complications==
[[File:Needle safety demo.gif|thumb|right|Using safety needles that prevent more than one use and accidental injections ensures sterility and prevents [[needlestick injuries]].]]

As an injection necessitates piercing the skin, there is a risk of infection from [[bacteria]] or other organisms present in the environment or on the skin before the injection. This risk is minimized by using proper [[aseptic technique]] in preparing the injection and sanitizing the injection site before administration.<ref name=LippNurs7 />{{rp|369}} Intramuscular injections may also cause an abscess or gangrene at the injection site, depending on the specific medication and amount administered. There is also a risk of nerve or vascular injury if a nerve or blood vessel is inadvertently hit during injection. If single-use or sterilized equipment is not used, there is the risk of transmission of infectious disease between users, or to a practitioner who inadvertently injures themselves with a used needle, termed a [[needlestick injury]].<ref name="Polania" /><ref name=LippNurs7 />{{rp|372}}

===Site-specific complications===
Injections into the deltoid site in the arm can result in unintentional damage to the [[radial nerve|radial]] and [[axillary nerve]]s. In rare cases when not performed properly, the injection may result in shoulder dysfunction.<ref name="HVI">{{cite journal |last1=Cook |first1=Ian F |title=Best vaccination practice and medically attended injection site events following deltoid intramuscular injection |journal=Human Vaccines & Immunotherapeutics |date=4 May 2015 |volume=11 |issue=5 |pages=1184–1191 |doi=10.1080/21645515.2015.1017694|pmid=25868476 |pmc=4514326 |doi-access=free }}</ref> The most frequent complications of a deltoid injection include pain, redness, and inflammation around the injection site, which are almost always mild and last only a few days at most.<ref name="Vaccine2017">{{cite journal |last1=Martín Arias |first1=L.H. |last2=Sanz Fadrique |first2=R. |last3=Sáinz Gil |first3=M. |last4=Salgueiro-Vazquez |first4=M.E. |title=Risk of bursitis and other injuries and dysfunctions of the shoulder following vaccinations |journal=Vaccine |date=September 2017 |volume=35 |issue=37 |pages=4870–4876 |doi=10.1016/j.vaccine.2017.07.055|pmid=28774564 }}</ref>

The dorsogluteal site of injection is associated with a higher risk of skin and tissue trauma, muscle [[Injection fibrosis|fibrosis]] or [[contracture]], [[hematoma]], nerve [[palsy]], [[paralysis]], and infections such as [[abscess]]es and [[gangrene]].<ref name="JBI" /> Furthermore, injection in the gluteal muscle poses a risk for damage to the [[sciatic nerve]], which may cause shooting pain or a sensation of burning. Sciatic nerve damage can also affect a person's ability to move their foot on the affected side, and other parts of the body controlled by the nerve. Damage to the sciatic nerve can be prevented by using the ventrogluteal site instead, and by selecting an appropriate size and length of needle for the injection.<ref name="JIMR2014">{{cite journal |last1=Jung Kim |first1=Hyun |last2=Hyun Park |first2=Sang |title=Sciatic nerve injection injury |journal=Journal of International Medical Research |date=August 2014 |volume=42 |issue=4 |pages=887–897 |doi=10.1177/0300060514531924|pmid=24920643 |doi-access=free }}</ref>

==Technique==
[[File:Intramuscular Injection.JPG|thumb|right|An intramuscular injection is performed perpendicular to the skin, close to a 90 degree angle.]]
[[File:Needle-insertion-angles-1.png|thumb|right|Comparison of angle of intramuscular injection with other injection types]]
An intramuscular injection can be administered in multiple different muscles of the body. Common sites for intramuscular injection include: [[Deltoid muscle|deltoid]], [[Gluteal muscles|dorsogluteal]], [[Rectus femoris muscle|rectus femoris]], [[Vastus lateralis muscle|vastus lateralis]] and [[ventrogluteal]] muscles.<ref name="JBI" /><ref>{{Citation|last=Bolger|first=Gordon T.|title=Routes of Drug Administration|date=2018-01-01|url=http://www.sciencedirect.com/science/article/pii/B9780128012383110992|work=Reference Module in Biomedical Sciences|publisher=Elsevier|language=en|doi=10.1016/b978-0-12-801238-3.11099-2|isbn=978-0-12-801238-3|access-date=2020-11-25|url-access=subscription}}</ref> Sites that are bruised, tender, red, swollen, inflamed or scarred are generally avoided.<ref name="Taylor">{{cite book |last1=Taylor |first1=Carol |title=Fundamentals of nursing: the art and science of nursing care |date=2011 |publisher=Wolters Kluwer Health and Lippincott Williams & Wilkins |isbn=978-0-7817-9383-4 |edition=7th |location=Philadelphia }}</ref> The specific medication and amount being administered will influence the decision of the specific muscle chosen for injection.

The injection site is first cleaned using an antimicrobial and allowed to dry. The injection is performed in a quick, darting motion perpendicular to the skin, at an angle between 72 and 90 degrees. The practitioner will stabilize the needle with one hand while using their other hand to depress the plunger to slowly inject the medication – a rapid injection causes more discomfort. The needle is withdrawn at the same angle inserted. Gentle pressure may be applied with gauze if bleeding occurs.<ref name=Lippincott>{{cite book |last1=Lynn |first1=Pamela |last2=Taylor |first2=Carol |title=Lippincott photo atlas of medication administration |date=2019 |publisher=Wolters Kluwer |location=Philadelphia, PA |isbn=978-1-9751-2136-5 |pages=39–40 |edition=Sixth}}</ref> Pressure or gentle massage of the muscle following injection may reduce the risk of pain.<ref name=JAN2019 />

=== Aspiration ===
Aspirating for blood to rule out injecting into a blood vessel is not recommended by the US [[Centers for Disease Control and Prevention|CDC]], [[Public Health Agency of Canada]], or [[Norwegian Institute of Public Health|Norway Institute of Public Health]], as the injection sites do not contain large blood vessels and aspiration results in greater pain.<ref name="CDCPink">{{cite book|url=https://www.cdc.gov/vaccines/pubs/pinkbook/vac-admin.html|title=The Pinkbook|date=25 September 2019|publisher=[[Centers for Disease Control and Prevention|CDC]]|language=en-us|chapter=Vaccine Administration|quote=Aspiration is not recommended before administering a vaccine.|access-date=12 September 2020|author1=JoEllen Wolicki |author2=Elaine Miller}}</ref><ref>{{cite web|date=2020-12-02|title=Vaccine administration practices: Canadian Immunization Guide|url=https://www.canada.ca/en/public-health/services/publications/healthy-living/canadian-immunization-guide-part-1-key-immunization-information/page-8-vaccine-administration-practices.html |access-date=2021-05-25|website=Public Health Agency of Canada |quote=Aspiration before injection of vaccine is not recommended, as there are no large blood vessels at the recommended immunization sites and not aspirating before injection has been demonstrated to reduce pain.}}</ref><ref>{{cite web|title=Praktisk info om vaksinasjon|url=https://www.fhi.no/nettpub/vaksinasjonsveilederen-for-helsepersonell/vaksinasjon/praktisk-vaksinasjon/ |access-date=2021-05-25|website=Folkehelseinstituttet|date=9 April 2008 |language=no|quote=However, it is not recommended to aspirate before intramuscular and subcutaneous vaccine injection provided that the vaccine is placed in the appropriate place … does not involve the risk of injecting intravenously because there are no large blood vessels in these sites. Aspiration can cause the vaccination to be more painful because it takes longer to give the vaccine}}</ref> There is no evidence that aspiration is useful to increase safety of intramuscular injections when injecting in a site other than the dorsogluteal site.<ref name="Nurs2015" /> 

Aspiration was recommended by the [[Danish Health Authority]] for [[COVID-19 vaccine|COVID-19 vaccines]] for a time to investigate the potential rare risk of blood clotting and bleeding, but it is no longer a recommendation.<ref>{{cite web|date=2021-03-20|title=Covid-19 vacciner skal gives med aspiration før injektion|url=https://dsr.dk/politik-og-nyheder/nyhed/covid-19-vacciner-skal-gives-med-aspiration-foer-injektion|access-date=2021-05-25|website=Politik og nyheder, DSR|language=da|quote=The Danish Health and Medicines Authority's guidelines have long recommended this, and now the Statens Serum Institut is following suit.|archive-date=2021-03-22|archive-url=https://web.archive.org/web/20210322170314/https://dsr.dk/politik-og-nyheder/nyhed/covid-19-vacciner-skal-gives-med-aspiration-foer-injektion|url-status=dead}}</ref><ref>{{cite web|last=name|title=Intramuskulær injektion på børn og voksne|url=https://www.ssi.dk/vaccinationer/injektionsteknik/intramuskulaer-injektion-beorn-og-voksne |access-date=2023-10-04|website=Statens Serum Institut |language=da|quote=It has previously been recommended to aspirate before injection with Covid-19 vaccines in relation to investigation of a possible connection between injection with Vaxzevria® and the occurrence of rare and serious side effects. However, this is no longer a recommendation and Covid-19 vaccines can be injected without prior aspiration.}}</ref>

=== Z-track method ===
The Z-track method is a method of administering an IM injection that prevents the medication being tracked through the subcutaneous tissue, sealing the medication in the muscle, and minimizing irritation from the medication. Using the Z-track technique, the skin is pulled laterally, away from the injection site, before the injection; then the medication is injected, the needle is withdrawn, and the skin is released. This method can be used if the overlying tissue can be displaced.<ref>{{cite book |last1=Doyle|first1=Glynda Rees|last2=McCutcheon|first2=Jodie Anita|date=2015 |chapter=7.4 Intramuscular Injections |chapter-url=https://opentextbc.ca/clinicalskills/chapter/6-8-iv-push-medications-and-saline-lock-flush/ |title=Clinical Procedures for Safer Patient Care |publisher=BCcampus |language=en}}</ref>

===Injection sites===
The deltoid muscle in the outer portion of the upper arm is used for injections of small volume, usually equal to or less than 1&nbsp;mL. This includes most intramuscular vaccinations.<ref name="JBI" /> It is not recommended to use the deltoid for repeated injections due to its small area, which makes it difficult to space out injections from each other.<ref name="JBI">The Joanna Briggs Institute. Recommended Practice. Injection: Intramuscular. The Joanna Briggs Institute EBP Database, from the JBI@Ovid database, published 2019; JBI2138. Accessed on 12 September 2020.</ref> The deltoid site is located by locating the lower edge of the [[acromion process]], and injecting in the area which forms an upside down triangle with its base at the acromion process and its midpoint in line with the [[axilla|armpit]].<ref name="Taylor" /> An injection into the deltoid muscle is commonly administered using a 1-inch long needle, but may use a {{frac|5|8}}-inch long needle for younger people or very frail elderly people.<ref name=Vaccine2017 />

The ventrogluteal site on the hip is used for injections which require a larger volume to be administered, greater than 1&nbsp;mL, and for medications which are known to be irritating, viscous, or oily. It is also used to administer [[narcotic]] medications, [[Antibiotics|antibiotic]]s, [[sedative]]s and [[Antiemetic|anti-emetic]]s.<ref name="JBI" /> The ventrogluteal site is located in a triangle formed by the [[anterior superior iliac spine]] and the [[iliac crest]], and may be located using a hand as a guide.<ref name="Taylor" /> The ventrogluteal site is less painful for injection than other sites such as the deltoid site.<ref name="JAN2019">{{cite journal |last1=Şanlialp Zeyrek |first1=Arife |last2=Takmak |first2=Şenay |last3=Kurban |first3=Nevin Kuzu |last4=Arslan |first4=Sümeyye |title=Systematic review and meta-analysis: Physical-procedural interventions used to reduce pain during intramuscular injections in adults |journal=Journal of Advanced Nursing |date=December 2019 |volume=75 |issue=12 |pages=3346–3361 |doi=10.1111/jan.14183|pmid=31452229 |s2cid=201786789 }}</ref>

The [[vastus lateralis]] site is used for infants less than 7 months old and people who are unable to walk or who have loss of muscular tone.<ref name="JBI" /> The site is located by dividing the front [[thigh]] into thirds vertically and horizontally to form nine squares; the injection is administered in the outer middle square.<ref name=Taylor/> This site is also the usual site of administration for [[epinephrine autoinjector]]s, which are used in the outer thigh, corresponding to the location of the vastus lateralis muscle.<ref>{{cite web|url=https://medlineplus.gov/druginfo/meds/a603002.html|title=Epinephrine Injection|website=[[MedlinePlus]]}} Last revised 03/15/2017</ref>

The dorsogluteal site of the buttock site is not routinely used due to its location near major [[blood vessel]]s and [[nerve]]s, as well as having inconsistent depth of [[adipose tissue]].<ref>{{cite journal |last1=Zimmermann |first1=Polly Gerber |title=Revisiting IM Injections |journal=American Journal of Nursing |date=February 2010 |volume=110 |issue=2 |pages=60–61 |doi=10.1097/01.NAJ.0000368058.72729.c6|pmid=20107407 }}</ref> Many injections in this site do not penetrate deep enough under the skin to be correctly administered in the muscle.<ref name="JBI" /><ref>{{cite journal |last1=Farley |first1=HF |last2=Joyce |first2=N |last3=Long |first3=B |last4=Roberts |first4=R |title=Will that IM needle reach the muscle? |journal=The American Journal of Nursing |date=December 1986 |volume=86 |issue=12 |pages=1327, 1331 |pmid=3641525}}</ref> While current [[evidence-based practice]] recommends against using this site, many healthcare providers still use this site, often due to a lack of knowledge about alternative sites for injection.<ref>{{cite journal |last1=Cocoman |first1=Angela |last2=Murray |first2=John |title=Recognizing the evidence and changing practice on injection sites |journal=British Journal of Nursing |date=October 2010 |volume=19 |issue=18 |pages=1170–1174 |doi=10.12968/bjon.2010.19.18.79050|pmid=20948472 }}</ref> 
This site is located by dividing the buttock into four using a cross shape, and administering the injection in the upper outer quadrant. This is the only intramuscular injection site for which aspiration is recommended of the syringe before injection, due to higher likelihood of accidental [[Intravenous therapy|intravenous administration]] in this area.<ref name="JBI" /> However, aspiration is not recommended by the [[US CDC|Centers for Disease Control and Prevention]], which considers it outdated for any intramuscular injection.<ref name="Lippincott" />

{{multiple image
|header=Sites for administration of intramuscular injections
|direction=horizontal | align=center | total_width = 1000px
|image1=Im-deltoid (cropped).png
|alt1=Deltoid site
|caption1=Diagram showing the [[deltoid muscle|deltoid]] site for intramuscular injection
|image2=Im-ventrogluteal-300x244.png
|alt2=Ventrogluteal site
|caption2=Ventrogluteal and rectus femoris sites for intramuscular injection
|image3=Injection Sites Intramuscular Thigh Adult.png
|alt3=Vastus lateralis site in adult
|caption3=Vastus lateralis site of administration in an adult
|image4=Injection Sites Intramuscular Thigh Child.png
|alt4=Vastus lateralis site in child
|caption4=Vastus lateralis site of administration in an infant or young child
}}

===Special populations===
Some populations require a different injection site, needle length, or technique. In very young or weak elderly patients, a normal-length needle may be too long to inject properly. In these patients, a shorter needle is indicated to avoid injecting too deeply.<ref name="Needles">{{cite journal |last1=Beirne |first1=Paul V |last2=Hennessy |first2=Sarah |last3=Cadogan |first3=Sharon L |last4=Shiely |first4=Frances |last5=Fitzgerald |first5=Tony |last6=MacLeod |first6=Fiona |title=Needle size for vaccination procedures in children and adolescents |journal=Cochrane Database of Systematic Reviews |date=9 August 2018 |volume=2018 |issue=8 |pages=CD010720 |doi=10.1002/14651858.CD010720.pub3|pmid=30091147 |pmc=6513245 }}</ref> It is also recommended to consider using the anterolateral thigh as an injection site in infants under one year old.<ref name=Needles />

To help infants and children cooperate with injection administration, the [[Advisory Committee on Immunization Practices]] in the United States recommends using distractions, giving something sweet, and rocking the baby side to side. In people who are overweight, a 1.5-inch needle may be used to ensure the injection is given below the [[subcutaneous tissue|subcutaneous]] layer of skin, while a {{frac|5|8}}-inch needle may be used for people who weigh under {{convert|60|kg|lb}}. In any case, the skin does not need to be pinched up before injecting when the appropriate length needle is used.<ref name="ACIP">{{cite web |title=ACIP Vaccine Administration Guidelines for Immunization {{!}} Recommendations {{!}} CDC |url=https://www.cdc.gov/vaccines/hcp/acip-recs/general-recs/administration.html |website=www.cdc.gov |publisher=[[Centers for Disease Control]] |access-date=12 September 2020 |language=en-us |date=21 June 2019}}</ref>

==History==
Injections into muscular tissue may have taken place as early as the year 500 AD. Beginning in the late 1800s, the procedure began to be described in more detail and techniques began to be developed by physicians. In the early days of intramuscular injections, the procedure was performed almost exclusively by physicians.<ref name="Nursing2002"/> After the introduction of [[antibiotics]] in the middle of the 20th century, nurses began preparing equipment for intramuscular injections as part of their delegated duties from physicians, and by 1961 they had "essentially taken over the procedure".<ref name="Nursing2002"/> Until this delegation became virtually universal, there were no uniform procedures or education for nurses in proper administration of intramuscular injections, and complications from improper injection were common.<ref name="Nursing2002"/>

Intramuscular injections began to be used for administration of vaccines for [[diphtheria]] in 1923, [[pertussis|whooping cough]] in 1926, and [[tetanus]] in 1927.<ref name="VacHist">{{cite journal |last1=Hebert |first1=CJ |last2=Hall |first2=CM |last3=Odoms |first3=LN |title=Lessons learned and applied: what the 20th century vaccine experience can teach us about vaccines in the 21st century. |journal=Human Vaccines & Immunotherapeutics |date=May 2012 |volume=8 |issue=5 |pages=560–8 |doi=10.4161/hv.19204 |pmid=22617834|pmc=3495718 |doi-access=free }}</ref> By the 1970s, researchers and instructors began forming guidance on injection site and technique to reduce the risk of injection complications and side effects such as pain.<ref name="Nursing2002"/> Also in the early 1970s, [[botulinum toxin]] began to be injected into muscles to intentionally paralyze them for therapeutic reasons, and later for cosmetic reasons.<ref>{{cite journal |last1=Monheit |first1=GD |last2=Pickett |first2=A |title=AbobotulinumtoxinA: A 25-Year History. |journal=Aesthetic Surgery Journal |date=1 May 2017 |volume=37 |issue=suppl_1 |pages=S4–S11 |doi=10.1093/asj/sjw284 |pmid=28388718|pmc=5434488 |doi-access=free }}</ref> Until the 2000s, aspiration after inserting the needle was recommended as a safety measure, to ensure the injection was being administered in a muscle and not inadvertently in a vein. However, this is no longer recommended as evidence shows no safety benefit and it lengthens the time taken for injection, which causes more pain.<ref name="ACIP" />

==Veterinary medicine==
In animals common sites for intramuscular injection include the [[Quadriceps femoris muscle|quadriceps]], the lumbodorsal muscles, and the triceps muscle.<ref>{{cite web |date=Dec 12, 2017 |title=SOP: Injections in Dogs and Cats |url=https://ouv.vt.edu/content/dam/ouv_vt_edu/sops/small-animal/sop-dogs-and-cats-injections.pdf |website=Virginia Tech}}</ref>

==See also==
* [[Subcutaneous injection]]
* [[Intradermal injection]]
* [[Intravenous injection]]

==References==
{{Reflist}}

==External links==
* {{MeshName|Injections,+Intramuscular}}
* [https://www.cdc.gov/mmwr/preview/mmwrhtml/rr54e713a1.htm Prevention and Control of Influenza, Recommendations of ACIP]

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{{Medical resources}}
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[[Category:Medical treatments]]
[[Category:Routes of administration]]
[[Category:Dosage forms]]
[[Category:Injection (medicine)]]
[[Category:Muscular system]]