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Stromectol Side Effects

Generic name: ivermectin

Medically reviewed by Last updated on Aug 28, 2023.

Note: This document contains side effect information about ivermectin. Some dosage forms listed on this page may not apply to the brand name Stromectol.

Applies to ivermectin: oral tablet.

Serious side effects of Stromectol

Along with its needed effects, ivermectin (the active ingredient contained in Stromectol) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking ivermectin:

More common

Less common


Incidence not known

Get emergency help immediately if any of the following symptoms of overdose occur while taking ivermectin:

Symptoms of overdose

Other side effects of Stromectol

Some side effects of ivermectin may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

For Healthcare Professionals

Applies to ivermectin: compounding powder, oral tablet.


Ivermectin (the active ingredient contained in Stromectol) is well tolerated compared to other microfilaricidal agents (i.e., thiabendazole, diethylcarbamazine). Adverse reactions (i.e., pruritus, fever, rash, myalgia, headache) occur commonly during the first 3 days after treatment and appear to be related to the extent of parasitic infection and systemic mobilization and killing of microfilariae. The majority of reactions can usually be treated with aspirin, acetaminophen and/or antihistamines. Adverse effects tend to occur with lesser frequency during periods of retreatment.[Ref]


Ocular side effects have included eyelid edema, anterior uveitis, blurred vision, conjunctivitis, limbitis, punctate opacity, keratitis, abnormal sensation in the eyes, and chorioretinitis/choroiditis; however, these effects are also associated with the disease onchocerciasis. Loss of vision has occurred rarely but usually resolved without corticosteroid treatment. Conjunctival hemorrhage has been reported during postmarketing experience in patients treated for onchocerciasis.[Ref]


Worsening of Mazzotti reactions, including arthralgia, synovitis, lymph node enlargement and tenderness, pruritus, skin involvement (including edema, papular and pustular or frank urticarial rash), and fever, has been reported during the first 4 days following treatment for onchocerciasis.

Nervous system

Nervous system side effects have included dizziness, headache, somnolence, vertigo, and tremor. Serious or fatal encephalopathy has been reported rarely in patients with onchocerciases, and heavily infected with Loa loa, either spontaneously or after treatment with ivermectin (the active ingredient contained in Stromectol) Seizures have been reported during postmarketing experience.[Ref]


Gastrointestinal side effects have included anorexia, constipation, diarrhea, nausea, vomiting, and abdominal distention.[Ref]


Other side effects have included asthenia, fatigue, abdominal pain, chest discomfort, facial edema, and peripheral edema.


Hematologic side effects have included decreased leukocyte count (3%), eosinophilia (3%), and increased hemoglobin (1%). Hematomatous swellings associated with prolonged prothrombin times have been reported, but the clinical significance is unknown. Leukopenia and anemia have been reported in at least one patient.[Ref]


Hepatic side effects have included elevated ALT and/or AST. Elevated liver enzymes, elevated bilirubin, and hepatitis have been reported during postmarketing experience.[Ref]


Cardiovascular side effects have included tachycardia and orthostatic hypotension. EKG changes, including prolonged PR interval, flattened T waves and peaked T waves, have been reported in single cases. Hypotension (primarily orthostatic hypotension) has been reported during postmarketing experience.[Ref]


Dermatologic side effects have included pruritus, rash, and urticaria. Toxic epidermal necrolysis and Stevens-Johnson syndrome have been reported during postmarketing experience.


Respiratory side effects have included worsening bronchial asthma, laryngeal edema, and dyspnea.[Ref]


Musculoskeletal side effects have included myalgia.


Renal side effects have included rare transient proteinuria.[Ref]

Frequently asked questions


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8. Ette EI, Thomas WO, Achumba JI. Ivermectin: a long-acting microfilaricidal agent. DICP. 1990;24:426-33.

9. Product Information. Stromectol (ivermectin). Merck & Co., Inc. 2001.

10. Elmogy M, Fayed H, Marzok H, Rashad A. Oral ivermectin in the treatment of scabies. Int J Dermatol. 1999;38:926-8.

11. Homeida MM, Bagi IA, Ghalib HW, el Sheikh H, Ismail A, Yousif MA, Sulieman S, Ali HM, Bennett JL, Williams J. Prolongation of prothrombin time with ivermectin. Lancet. 1988;1:1346-7.

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.