Side effect

From Wikipedia, the free encyclopedia

In medicine, a side effect is an effect, whether therapeutic or adverse, that is secondary to the one intended; although the term is predominantly employed to describe adverse effects, it can also apply to beneficial, but unintended, consequences of the use of a drug. Developing drugs is a complicated process, because no two people are exactly the same, so even drugs that have virtually no side effects, might be difficult for some people. Also, it is difficult to make a drug that targets one part of the body but that does not affect other parts,[1] the fact that increases the risk of side effects in the untargeted parts.

Occasionally, drugs are prescribed or procedures performed specifically for their side effects; in that case, said side effect ceases to be a side effect and is now an intended effect. For instance, X-rays were historically (and are currently) used as an imaging technique; the discovery of their oncolytic capability led to their employ in radiotherapy (ablation of malignant tumours).

Frequency of side effects[edit]

The World Health Organization and other health organisations characterise the probability or chance of experiencing side effects as:[2][3]

  • Very common, ≥ 110
  • Common (frequent), 110 to 1100
  • Uncommon (infrequent), 1100 to 11000
  • Rare, 11000 to 110000
  • Very rare, < 110000

The European Commission recommends that the list should contain only effects where "at least a reasonable possibility" exists that it is caused by the drug and the frequency "should represent crude incidence rates (and not differences or relative risks calculated against placebo or other comparator)".[4] That is, the frequency describes how often symptoms appear after taking the drug, not caused by the drug. Both health care providers[5] and lay people[6] misinterpret the frequency of side effects as describing the increase in frequency caused by the drug.

Examples of therapeutic side effects[edit]

Possible side effects of nicotine.[7][8]

Examples of undesirable/unwanted side effects[edit]

  • Echinacea – more than 20 different types of reactions have been reported, including asthma attacks, loss of pregnancy, hives, swelling, aching muscles and gastrointestinal upsets.[20]
  • Feverfew – pregnant women should avoid using this herb, as it can trigger uterine contractions which could lead to premature labour or miscarriage.[21]
  • Asteraceae plants – which include feverfew, echinacea, dandelion and chamomile. Side effects include allergic dermatitis and hay fever.[citation needed]

See also[edit]

  • 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


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  4. ^ "A Guideline on Summary of Product Characteristics" (PDF). European commission. 1 September 2009.{{cite web}}: CS1 maint: url-status (link)
  5. ^ Mühlbauer V, Mühlhauser I (November 2015). "Understanding adverse drug reactions in package leaflets - an exploratory survey among health care professionals". BMC Health Services Research. 15 (1): 505. doi:10.1186/s12913-015-1160-1. PMC 4641349. PMID 26554666.
  6. ^ Mühlbauer V, Prinz R, Mühlhauser I, Wegwarth O (13 September 2018). "Alternative package leaflets improve people's understanding of drug side effects-A randomized controlled exploratory survey". PLOS ONE. 13 (9): e0203800. Bibcode:2018PLoSO..1303800M. doi:10.1371/journal.pone.0203800. PMC 6136776. PMID 30212555.
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  10. ^ Gracer R (February 2007). "The Buprenorphine Effect on Depression" (PDF). National Alliance of Advocates for Buprenorphine Treatment. Retrieved 19 September 2015.
  11. ^ Bodkin JA, Zornberg GL, Lukas SE, Cole JO (February 1995). "Buprenorphine treatment of refractory depression". Journal of Clinical Psychopharmacology. 15 (1): 49–57. doi:10.1097/00004714-199502000-00008. PMID 7714228.
  12. ^ Leehey K (1 August 2003). "Mood Stabilizers for Bipolar Disorder (Manic Depressive)". Archived from the original on 13 November 2011. Retrieved 17 August 2011.
  13. ^ a b Wing DA, Powers B, Hickok D (April 2010). "U.S. Food and Drug Administration drug approval: slow advances in obstetric care in the United States". Obstetrics and Gynecology. 115 (4): 825–833. doi:10.1097/AOG.0b013e3181d53843. PMID 20308845.
  14. ^ Shen WW, Mahadevan J, Hofstatter L, Sata LS (July 1983). "Doxepin as a potent H2 and H2 antihistamine for epigastric distress". The American Journal of Psychiatry. 140 (7): 957–8. doi:10.1176/ajp.140.7.957. PMID 6859336. Archived from the original on 4 September 2011.
  15. ^ "Off-label Use of Gabapentin" (PDF). Idaho Drug Utilization Review, educational leaflet. 2004. Archived from the original (PDF) on 9 August 2007.
  16. ^ "Pregnancy". (New Medical Information and Health Information). Archived from the original on 11 October 2008.
  17. ^ Deem SG. "Premature Ejaculation". Archived from the original on 1 December 2008. Retrieved 17 August 2011.
  18. ^ Gelenberg AJ, Freeman MP, Markowitz JC, Rosenbaum JF, Thase ME, Trivedi MH, Silbersweig DA (2010). "Practice guideline for the treatment of patients with major depressive disorder" (PDF). Am J Psychiatry. American Psychiatric Association. 167 (Suppl 10): 9–118.{{cite journal}}: CS1 maint: date and year (link)
  19. ^ Cheshire WP, Fealey RD (2008). "Drug-induced hyperhidrosis and hypohidrosis: incidence, prevention and management". Drug Safety. 31 (2): 109–26. doi:10.2165/00002018-200831020-00002. PMID 18217788. S2CID 23041000.
  20. ^ "Filagra Vs Fildena". 23 February 2017. Archived from the original on 3 July 2017.
  21. ^ Wells RE, Turner DP, Lee M, Bishop L, Strauss L (April 2016). "Managing Migraine During Pregnancy and Lactation". Current Neurology and Neuroscience Reports. 16 (4): 40. doi:10.1007/s11910-016-0634-9. PMID 27002079. S2CID 10098257.

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