Editing Redback spider (section)

===Treatment===
Treatment is based on the severity of the envenomation. The majority of cases do not require medical care, and patients with localised pain, swelling and redness usually require only local application of ice and simple oral [[analgesia]] such as [[paracetamol]]. Pressure immobilisation of the wound site is not recommended. Keeping the victim still and calm is beneficial.<ref name="Slaughter"/><ref>{{cite web|url=http://www.ambulance.nsw.gov.au/Media/docs/funnel_web_and_redback_spider_bites-5d64cbaa-fbb8-439f-b281-0d0c4d380cbb-0.pdf|title=Funnel Web and Redback Spider Bites: First Aid Advice|author=New South Wales Ambulance Service|year=2008|work=Standard Operating Policy|publisher=State Government of New South Wales|access-date=13 October 2013|archive-date=6 March 2014|archive-url=https://web.archive.org/web/20140306160437/http://www.ambulance.nsw.gov.au/Media/docs/funnel_web_and_redback_spider_bites-5d64cbaa-fbb8-439f-b281-0d0c4d380cbb-0.pdf|url-status=live}}</ref>

Hospital assessment is recommended if simple pain relief does not resolve local pain, or systemic symptoms occur.{{sfn|White|2013|p=198}}<ref name="Murray">{{cite book | last = Murray | first = L. | author2 = Daly, F.| author3 = Little, M.| author4 = Cadogan, M.| title = Toxicology Handbook| publisher = Churchill Livingstone| location = Sydney | year = 2011 | pages = 470–79| isbn = 978-0-7295-3939-5}}</ref> [[Opioid]] analgesics may be necessary to relieve pain.<ref name="lancet"/> Antivenom has been historically given for adults suffering severe local pain or systemic symptoms consistent with latrodectism, which include pain and swelling spreading proximally from site, distressing local or systemic pain, chest pain, abdominal pain, or excessive sweating ([[diaphoresis]]).{{sfn|White|2013|pp=203–04}} A significant proportion of bites will not result in envenomation or any symptoms developing; around 2–20% of bite victims have been treated with antivenom.{{efn|The exact fraction of bites that require antivenom is difficult to quantify, because many bites are unreported. Figures from the manufacturer show that 344 cases required antivenom treatment in 1995,<ref name=White1998/> and in 2011 the figure was around 200.<ref name=Booth2008/> Estimates for the total number of bites range from 2,000<ref name=Nicholson2003/> to 10,000.<ref name=White1998/> These estimates correspond to a broad range of about 2–17%, and reports have generally expressed this as "around" or "under" 20%.<ref name=Nicholson2003/><ref name=White1998/> Two studies of redback victims who attended hospitals found that 6/23 (26%)<ref name="isbister"/> and 32/150 (21%)<ref name="jelinek1989"/> received antivenom.}}<ref name=White1998>{{cite journal |author=White, J. |title=Envenoming and Antivenom use in Australia |journal=Toxicon |volume=36 |issue=11 |pages=1483–92 |year=1998 |pmid=9792162 |doi=10.1016/S0041-0101(98)00138-X|bibcode=1998Txcn...36.1483W }}</ref> In an Australian study of 750 emergency hospital admissions for spider bites where the spider was definitively identified, 56 were from redbacks. Of these, 37 had significant pain lasting over 24 hours. Only six were treated with the antivenom.<ref name="bite study">{{Cite journal | last1 = Isbister | first1 = G. K. | last2 = Gray | first2 = M. R. | title = A Prospective Study of 750 Definite Spider Bites, with Expert Spider Identification | doi = 10.1093/qjmed/95.11.723 | journal = QJM | volume = 95 | issue = 11 | pages = 723–31 | year = 2002 | pmid =  12391384| doi-access = free }}</ref>

The antivenom manufacturer's product information recommends one vial, although more has been used.{{sfn|White|2013|p=312}} Past guidelines indicated two vials, with a further two vials recommended if symptoms did not resolve within two hours, however recent guidelines state "antivenom is sometimes given if there is a history, symptoms and signs consistent with systemic envenoming, and severe pain unresponsive to oral analgesics ... however recent trials show antivenom has a low response rate little better than placebo, and any effect is less than might be achieved with optimal use of standard analgesics."{{sfn|White|2013|pp=203–04}}<ref name=":2" /> The antivenom can be given by injection [[Intramuscular injection|intramuscularly]] (IM) or [[Intravenous therapy|intravenously]] (IV). The manufacturer recommends IM use, with IV administration reserved for life-threatening cases.<ref name="proinfo">{{cite web|url=http://www.csl.com.au/s1/cs/auhq/1196562765747/Web_Product_C/1196562644318/ProductDetail.htm|title=Redback Antivenom Product Information|year=2009|publisher=CSL Ltd|location=Melbourne, Australia|access-date=10 September 2013|archive-date=21 September 2013|archive-url=https://web.archive.org/web/20130921055927/http://www.csl.com.au/s1/cs/auhq/1196562765747/Web_Product_C/1196562644318/ProductDetail.htm|url-status=live}}</ref> In January 2008 toxicologist Geoffrey Isbister suggested IM antivenom was not as effective as IV antivenom,<ref name="isbister"/><ref>{{cite journal |doi=10.1046/j.1442-2026.2002.00356.x |author=Isbister, Geoff |title=Failure of Intramuscular Antivenom in Redback Spider Envenoming |journal=Emergency Medicine Australasia |volume=14 |issue=4 |pages=436–39 |year=2002 |pmid=12534488}}</ref> after proposing that IM antivenom took longer to reach the [[Serum (blood)|blood serum]].<ref name="serum study">{{Cite journal | last1 = Isbister | first1 = G. K. | last2 = O'Leary | first2 = M. | last3 = Miller | first3 = M. | last4 = Brown | first4 = S. G. A. | last5 = Ramasamy | first5 = S. | last6 = James | first6 = R. | last7 = Schneider | first7 = J. S. | doi = 10.1111/j.1365-2125.2007.03004.x | title = A comparison of serum antivenom concentrations after intravenous and intramuscular administration of redback (widow) spider antivenom | journal = British Journal of Clinical Pharmacology | volume = 65 | issue = 1 | pages = 139–43 | year = 2008 | pmid =  18171334| pmc =2291270 }}</ref> Isbister subsequently found the difference between IV and IM routes of administration was, at best, small and did not justify routinely choosing one route over the other.<ref>{{cite journal|vauthors=Isbister GK, Brown SG, Miller M, Tankel A, Macdonald E, Stokes B, Ellis R, Nagree Y, Wilkes GJ, James R, Short A|title=A randomised controlled trial of intramuscular vs. intravenous antivenom for latrodectism—the RAVE study|journal=QJM|year=2008|volume=101|issue=7|pages=557–65|doi=10.1093/qjmed/hcn048|pmid=18400776|doi-access=free}}</ref>

These concerns led two handbooks to recommend IV in preference to IM administration in Australian practice.{{sfn|White|2013|p=205}}<ref name="Murray"/>{{efn|A 2006 questionnaire found that of 218 Emergency physicians, 34 used the antivenom IM exclusively, 36 used IM then IV, 63 IV exclusively and 80 had no preference—that is, there was no consensus for preferred route.<ref>{{cite journal|author1=Brown, Simon A. |author2=Isbister, Geoffrey K. |year=2007|title=Route of administration of redback spider bite antivenom: Determining clinician beliefs to facilitate Bayesian analysis of a clinical trial|journal=Emergency Medicine Australasia |volume=19|issue=5|pages=458–63 |doi=10.1111/j.1742-6723.2007.01014.x|pmid=17919219|s2cid=310139 }}</ref>}} Despite a long history of usage and anecdotal evidence of effectiveness, there is a lack of data from controlled studies confirming the antivenom's benefits.<ref name="lancet"/> In 2014 Isbister and others conducted a randomized controlled trial of intravenous antivenom versus placebo for Redback envenomation, finding the addition of antivenom did not significantly improve pain or systemic effects, while antivenom resulted in acute hypersensitivity reactions in 3.6 per cent of those receiving it.<ref name=":3">{{cite journal |doi=10.1016/j.annemergmed.2014.06.006 |pmid=24999282 |title=Randomized Controlled Trial of Intravenous Antivenom Versus Placebo for Latrodectism: The Second Redback Antivenom Evaluation (RAVE-II) Study |journal=Annals of Emergency Medicine |volume=64 |issue=6 |pages=620–8.e2 |year=2014 |last1=Isbister |first1=Geoffrey K. |last2=Page |first2=Colin B. |last3=Buckley |first3=Nicholas A. |last4=Fatovich |first4=Daniel M. |last5=Pascu |first5=Ovidiu |last6=MacDonald |first6=Stephen P.J. |last7=Calver |first7=Leonie A. |last8=Brown |first8=Simon G.A. |hdl=2123/14928 |url=https://ses.library.usyd.edu.au/bitstream/2123/14928/1/Isbister_et_al_2014.pdf |hdl-access=free |access-date=24 September 2019 |archive-date=20 July 2018 |archive-url=https://web.archive.org/web/20180720071527/https://ses.library.usyd.edu.au/bitstream/2123/14928/1/Isbister_et_al_2014.pdf |url-status=live }}</ref> The question of abandoning the antivenom on the basis of this and previous studies came up in the Annals of Emergency Medicine in 2015 where White and Weinstein argued that if the recommendations in the 2014 Isbister et al. paper were followed it would lead to abandonment of antivenom as a treatment option, an outcome White and Weinstein considered undesirable. Authors of the 2014 Isbister et al. paper responded in the same issue by suggesting patients for whom antivenom is considered should be fully informed "there is considerable weight of evidence to suggest it is no better than placebo", and in light of a risk of anaphylaxis and serum sickness,  "routine use of the antivenom is therefore not recommended".<ref name=":1">{{cite journal |doi=10.1016/j.annemergmed.2014.08.022 |pmid=25529159 |title=Latrodectism and Effectiveness of Antivenom |journal=Annals of Emergency Medicine |volume=65 |issue=1 |pages=123–24 |year=2015 |last1=White |first1=Julian |last2=Weinstein |first2=Scott A. }}</ref>

Before the introduction of antivenom, [[benzodiazepine]]s and intravenous [[calcium gluconate]] were used to relieve symptoms of pain and distress,<ref name="rauber83" /><ref>{{cite journal|last=Braitberg|first=George|year=2009|title=Spider bites: Assessment and management|url=http://www.racgp.org.au/afp/200911/200911braithberg.pdf|journal=Australian Family Physician|type=Review|volume=38|issue=11|pages=862–67|pmid=19893831|access-date=29 October 2013|archive-date=1 November 2013|archive-url=https://web.archive.org/web/20131101170857/http://www.racgp.org.au/afp/200911/200911braithberg.pdf|url-status=live}}</ref> although calcium is not recommended as its benefit has not been shown in clinical trials.{{sfn|White|2013|p=206}}

Studies support the safety of antivenom, with around a 5% chance of an acute reaction, 1–2% of [[anaphylaxis]] and 10% chance of a delayed reaction due to [[serum sickness]].<ref name="lancet"/> Nevertheless, it is recommended that an injection of [[adrenaline]] be ready and available in case it is needed to treat a severe anaphylactic reaction,<ref name="proinfo"/> and also that the antivenom from the vial be administered diluted in a 100 ml bag of intravenous solution for infusion over 30 minutes.{{sfn|White|2013|p=209}} While it is rare that patients report symptoms of envenomation lasting weeks or months following a bite,<ref name="isbister"/> there are case reports from the 1990s in which antivenom was reported to be effective in the relief of chronic symptoms when administered weeks or months after a bite.<ref>{{cite journal |author1=Banham, N. |author2=Jelinek, G. |author3=Finch, P. |title=Late Treatment with Antivenom in Prolonged Redback Spider Envenomation |journal=Medical Journal of Australia |volume=161 |issue=6 |pages=379–81 |year=1994 |pmid=8090117|type=Case report|doi=10.5694/j.1326-5377.1994.tb127492.x |s2cid=27782875 }}</ref><ref name="Wells">{{cite journal |author1=Wells, C. L. |author2=Spring, W. J. |title=Delayed but Effective Treatment of Red-back Spider Envenomation|journal=Medical Journal of Australia |volume=164 |issue=7 |page=447 |year=1996 |pmid= 8609868|type=Case report, letter|doi=10.5694/j.1326-5377.1996.tb122109.x |s2cid=31114115 }}</ref> However, in the vast majority of cases, it is administered within 24 hours.<ref name="sutherland"/>