Editing Side effect

{{Use dmy dates|date=April 2021}}
{{Short description|Outcome that is secondary to the one intended}}
{{About|side effects in the context of medicine|side effects in the context of computer science|Side effect (computer science)| other uses}}

In [[medicine]], a '''side effect''' is an effect of the use of a medicinal [[drug]] or other treatment, usually [[Adverse effect|adverse]] but sometimes beneficial,  that is unintended. Herbal and [[traditional medicine]]s also have side effects.

A drug or procedure usually used for a specific effect may be used specifically because of a beneficial side-effect; this is termed "[[off-label use]]" until such use is approved.<ref name="due">{{cite journal |vauthors=Due A |title=What are side effects? |journal=European Journal for Philosophy of Science |volume=13 |issue=1 |pages=16 |date=2023 |pmid=36936702 |pmc=10006551 |doi=10.1007/s13194-023-00519-8}}</ref> For instance, [[X-ray]]s have long been used as [[Radiography|an imaging technique]]; the discovery of their oncolytic capability led to their use in [[radiotherapy]] for ablation of [[Malignancy|malignant]] [[tumour]]s.

== Frequency of side effects ==

[[File:Side effects of nicotine.png|thumb|330px|Possible side effects of [[nicotine]]<ref name=Drugs.com>{{cite web|title=Nicotine Side Effects|url=https://www.drugs.com/sfx/nicotine-side-effects.html|publisher=Drugs.com }}</ref><ref name=Schraufnage2014>{{cite journal | vauthors = Schraufnagel DE, Blasi F, Drummond MB, Lam DC, Latif E, Rosen MJ, Sansores R, Van Zyl-Smit R | display-authors = 6 | title = Electronic cigarettes. A position statement of the forum of international respiratory societies | journal = American Journal of Respiratory and Critical Care Medicine | volume = 190 | issue = 6 | pages = 611–8 | date = September 2014 | pmid = 25006874 | doi = 10.1164/rccm.201407-1198PP | s2cid = 43763340 | url = https://figshare.com/articles/journal_contribution/10758143 }}</ref>]]

The [[World Health Organization]] and other health organisations characterise the probability of experiencing side effects as:<ref>{{cite web |url=http://www.webmd.com/drugs/2/drug-6111/misoprostol-oral/details/list-sideeffects |title=Common and Rare Side Effects for misoprostol oral}}</ref><ref>{{cite web |url=https://www.who.int/medicines/areas/quality_safety/safety_efficacy/trainingcourses/definitions.pdf |title=Definitions |date=8 May 2007<!--from PDF source-->|url-status=dead|archive-url=https://web.archive.org/web/20160304222413/http://www.who.int/medicines/areas/quality_safety/safety_efficacy/trainingcourses/definitions.pdf |archive-date=2016-03-04}}</ref>

* Very common, ≥ <sup>1</sup>'''⁄'''<sub>10</sub>
* Common (frequent), <sup>1</sup>'''⁄'''<sub>10</sub> to <sup>1</sup>'''⁄'''<sub>100</sub>
* Uncommon (infrequent), <sup>1</sup>'''⁄'''<sub>100</sub> to <sup>1</sup>'''⁄'''<sub>1000</sub>
* Rare, <sup>1</sup>'''⁄'''<sub>1000</sub> to <sup>1</sup>'''⁄'''<sub>10000</sub>
* Very rare, < <sup>1</sup>'''⁄'''<sub>10000</sub>
The [[European Commission]] recommends that the list should contain only effects where there is "at least a reasonable possibility" that they are caused by the drug and the frequency "should represent crude incidence rates (and not differences or relative risks calculated against placebo or other comparator)".<ref>{{Cite web|date=2009-09-01|title=A Guideline on Summary of Product Characteristics|url=https://ec.europa.eu/health/sites/default/files/files/eudralex/vol-2/c/smpc_guideline_rev2_en.pdf|website=[[European Commission]]}}</ref> The frequency describes how often symptoms appear ''after'' taking the drug, without assuming that they were necessarily ''caused by'' the drug. Both healthcare providers<ref>{{cite journal | vauthors = Mühlbauer V, Mühlhauser I | title = Understanding adverse drug reactions in package leaflets - an exploratory survey among health care professionals | journal = BMC Health Services Research | volume = 15 | issue = 1 | pages = 505 | date = November 2015 | pmid = 26554666 | pmc = 4641349 | doi = 10.1186/s12913-015-1160-1 | doi-access = free }}</ref> and lay people<ref>{{cite journal | vauthors = Mühlbauer V, Prinz R, Mühlhauser I, Wegwarth O | title = Alternative package leaflets improve people's understanding of drug side effects-A randomized controlled exploratory survey | journal = PLOS ONE | volume = 13 | issue = 9 | pages = e0203800 | date = 2018-09-13 | pmid = 30212555 | pmc = 6136776 | doi = 10.1371/journal.pone.0203800 | bibcode = 2018PLoSO..1303800M | doi-access = free }}</ref> misinterpret the frequency of side effects as describing the increase in frequency caused by the drug.

==Examples of therapeutic side effects==
{{See also|Serendipity}}
Most drugs and procedures have a multitude of reported adverse side effects; the information leaflets provided with virtually all drugs list possible side effects. Beneficial side effects are less common; some examples, in many cases of side-effects that ultimately gained regulatory approval as intended effects, are:
* [[Bevacizumab]] ([[Avastin]]), used to slow the growth of blood vessels, has been used against dry age-related [[macular degeneration]], as well as [[macular edema]] from diseases such as [[diabetic retinopathy]] and [[central retinal vein occlusion]].<ref>{{cite news |url=https://www.theguardian.com/medicine/story/0,,1799772,00.html |work=The Guardian |location=London |title=Drugs firm blocks cheap blindness cure | vauthors = Boseley S |date=17 June 2006 | access-date=2010-05-20}}</ref>
*[[Buprenorphine#Antidepressant features|Buprenorphine]] has been shown experimentally (1982–1995) to be effective against severe, refractory depression.<ref>{{cite web | vauthors = Gracer R |url=http://www.naabt.org/documents/The_Buprenorphine_effect_on_Depression.pdf |title=The Buprenorphine Effect on Depression |website=naabt.org |publisher=National Alliance of Advocates for Buprenorphine Treatment |date=February 2007 |access-date= 19 September 2015}}</ref><ref>{{cite journal | vauthors = Bodkin JA, Zornberg GL, Lukas SE, Cole JO | title = Buprenorphine treatment of refractory depression | journal = Journal of Clinical Psychopharmacology | volume = 15 | issue = 1 | pages = 49–57 | date = February 1995 | pmid = 7714228 | doi = 10.1097/00004714-199502000-00008 }}</ref>
* [[Bupropion]] (Wellbutrin), an [[anti-depressant]], also helps smoking cessation; this indication was later approved, and the name of the drug as sold for smoking cessation is Zyban. Bupropion branded as Zyban may be sold at a higher price than as Wellbutrin, so some physicians prescribe Wellbutrin for smoking cessation.{{Citation needed|date=December 2016}}
* [[Carbamazepine]] is an approved treatment for [[bipolar disorder]] and [[epileptic seizure]]s, but it has side effects useful in treating [[attention-deficit hyperactivity disorder]] (ADHD), [[schizophrenia]], [[phantom limb]] syndrome, [[paroxysmal extreme pain disorder]], [[neuromyotonia]], and [[post-traumatic stress disorder]].<ref>{{cite web | vauthors = Leehey K | url = http://www.leeheymd.com/charts/dep4_1.html | title = Mood Stabilizers for Bipolar Disorder (Manic Depressive) | archive-url = https://web.archive.org/web/20111113183807/http://www.leeheymd.com/charts/dep4_1.html | archive-date = 13 November 2011 | work = Leeheymd.com | date = 1 August 2003 | access-date = 17 August 2011 }}</ref>
* [[Dexamethasone]] and [[betamethasone]] in [[premature labor]], to enhance pulmonary maturation of the fetus.<ref name=wing>{{cite journal | vauthors = Wing DA, Powers B, Hickok D | title = U.S. Food and Drug Administration drug approval: slow advances in obstetric care in the United States | journal = Obstetrics and Gynecology | volume = 115 | issue = 4 | pages = 825–833 | date = April 2010 | pmid = 20308845 | doi = 10.1097/AOG.0b013e3181d53843 }}</ref>
* [[Doxepin]] has been used to treat [[angiodema|angioedema]] and severe allergic reactions due to its strong [[antihistamine]] properties.<ref>{{cite journal | vauthors = Shen WW, Mahadevan J, Hofstatter L, Sata LS | title = Doxepin as a potent H2 and H2 antihistamine for epigastric distress | journal = The American Journal of Psychiatry | volume = 140 | issue = 7 | pages = 957–8 | date = July 1983 | pmid = 6859336 | doi = 10.1176/ajp.140.7.957 | url = http://ajp.psychiatryonline.org/cgi/reprint/140/7/957 | url-status = live | archive-url = http://archive.wikiwix.com/cache/20110904040738/http://ajp.psychiatryonline.org/cgi/reprint/140/7/957 | archive-date = 2011-09-04 | url-access = subscription }}</ref>
* [[Gabapentin]], approved for treatment of [[seizures]] and [[postherpetic neuralgia]] in adults, has side effects which are useful in treating bipolar disorder, [[essential tremor]], [[hot flashes]], [[migraine]] prophylaxis, [[neuropathic pain]] syndromes, phantom limb syndrome, and [[restless leg syndrome]].<ref>{{cite web | url = http://idahodur.isu.edu/leaflets/2004/GABAPENTIN%20EDU%20LEAFLET%202004.pdf | title = Off-label Use of Gabapentin | archive-url = https://web.archive.org/web/20070809235342/http://idahodur.isu.edu/leaflets/2004/GABAPENTIN%20EDU%20LEAFLET%202004.pdf | archive-date = 9 August 2007 | work = Idaho Drug Utilization Review, educational leaflet| date = 2004 }}</ref>
* [[Hydroxyzine]], an antihistamine, is also used as an [[anxiolytic]].{{Citation needed|date=December 2016}}
* [[Magnesium sulfate]] in obstetrics for [[premature labor]] and [[preeclampsia]].<ref name=wing />
* [[Methotrexate]] (MTX), approved for the treatment of [[choriocarcinoma]], is frequently used for the medical treatment of an unruptured [[ectopic pregnancy]].<ref>{{cite web| archive-url= https://web.archive.org/web/20081011183525/http://drugs.nmihi.com/whd/pregnancy.html |url=http://drugs.nmihi.com/whd/pregnancy.html| archive-date= 11 October 2008 |title=Pregnancy |website=drugs.nmihi.com |publisher=(New Medical Information and Health Information)}}</ref>
* The [[SSRI]] medication [[sertraline]] is approved as an antidepressant but delays [[Ejaculation|sexual climax]] in men, and can be used to treat [[premature ejaculation]].<ref>{{cite web | vauthors = Deem SG |url=http://www.emedicine.com/med/topic643.htm |website=Emedicine.com |title=Premature Ejaculation | access-date= 2011-08-17 | url-status= live | archive-url= https://web.archive.org/web/20081201091923/http://www.emedicine.com/med/topic643.htm | archive-date= 2008-12-01}}</ref>
* [[Sildenafil]] was originally intended for [[pulmonary hypertension]]; subsequently, it was discovered that it also produces [[erection]]s, for which it was later approved.{{Citation needed|date=December 2016}}
* [[Terazosin]], an [[Alpha-1 blocker|α<sub>1</sub>-adrenergic antagonist]] approved to treat benign prostatic hyperplasia (enlarged prostate) and hypertension, is (one of several drugs) used off-label to treat drug induced [[Perspiration|diaphoresis]] and [[hyperhidrosis]] (excessive sweating).<ref>{{Cite journal |url=http://psychiatryonline.org/pb/assets/raw/sitewide/practice_guidelines/guidelines/mdd.pdf |title=Practice guideline for the treatment of patients with major depressive disorder|display-authors=3 | vauthors = Gelenberg AJ, Freeman MP, Markowitz JC, Rosenbaum JF, Thase ME, Trivedi MH, Silbersweig DA | journal = Am J Psychiatry | date =  2010 | volume = 167 | issue = Suppl 10 | pages = 9–118}}</ref><ref>{{cite journal | vauthors = Cheshire WP, Fealey RD | title = Drug-induced hyperhidrosis and hypohidrosis: incidence, prevention and management | journal = Drug Safety | volume = 31 | issue = 2 | pages = 109–26 | date = 2008 | pmid = 18217788 | doi = 10.2165/00002018-200831020-00002 | s2cid = 23041000 }}</ref>
* [[Thalidomide]], a drug sold [[over the counter]] from 1957 to 1961 as a [[tranquiliser]] and treatment for [[morning sickness]] of pregnancy, became notorious for causing tens of thousands of babies to be [[Teratology|born without limbs]] and with other conditions, or [[stillborn]]. The drug, though still [[List of thalidomide side effects|subject to other adverse side-effects]], is now used to treat [[cancer]]s and [[skin disorder]]s, and is on  the [[World Health Organization's List of Essential Medicines]].<ref name="WHO22nd">{{cite book| title = World Health Organization model list of essential medicines: 22nd list| year = 2021 | hdl = 10665/345533 | publisher = [[World Health Organization]]| location = Geneva | id = WHO/MHP/HPS/EML/2021.02 | hdl-access=free }}</ref>

== See also ==
* [[Adverse drug reaction]] (ADR), a harmful unintended result caused by taking medication
* [[Combined drug intoxication]]
* [[Conservative management]]
* [[Drug interaction|Drug-drug interaction]] (DDI), an alteration of the action of a drug caused by the administration of other drugs
* [[Paradoxical reaction]], an effect of a substance opposite to what would usually be expected
* [[Pharmacogenetics]], the use of genetic information to determine which type of drugs will work best for a patient
* [[Unintended consequences]]

== References ==
{{Reflist|2}}

== External links ==
* {{cite web | url = https://www.hc-sc.gc.ca/dhp-mps/medeff/index-eng.php | title = MedEffect Canada | work = Health Canada | date = 13 July 2011 }}
* {{cite web | url = https://www.who.int/medicines/areas/quality_safety/safety_efficacy/trainingcourses/definitions.pdf| work = World Health Organization | title = Definitions }}
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[[Category:Clinical pharmacology]]