Vermox Side Effects

Generic Name: mebendazole

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

Some side effects of Vermox may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.

For the Consumer

Applies to mebendazole: oral suspension, oral tablet chewable

Along with its needed effects, mebendazole (the active ingredient contained in Vermox) 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 as soon as possible if any of the following side effects occur while taking mebendazole:

  • Fever
  • skin rash or itching
  • sore throat and fever
  • unusual tiredness and weakness

Some side effects of mebendazole 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
  • Abdominal or stomach pain or upset
  • diarrhea
  • nausea or vomiting
  • Dizziness
  • hair loss
  • headache

For Healthcare Professionals

Applies to mebendazole: compounding powder, oral tablet chewable


Since mebendazole (the active ingredient contained in Vermox) is not well absorbed, few systemic side effects are reported. Side effects may be more likely and more severe in patients with underlying liver disease.


Gastrointestinal side effects have included nausea, vomiting, diarrhea, and abdominal pain, especially when the intestinal parasite burden is great.


Increased liver function tests have been associated with mebendazole (the active ingredient contained in Vermox) in patients with hepatic hydatid cysts.

Hepatic side effects have included transient changes in liver function tests and granulomatous hepatitis. These side effects have been reported when mebendazole was taken for prolonged periods and at dosages substantially above those recommended.


Bone marrow biopsy results during mebendazole-associated leukopenia or pancytopenia have revealed hypocellularity. These effects reverse upon drug discontinuation.

Hematologic side effects are unusual and reversible, but may be severe. Profound leukopenia, often accompanied by anemia and thrombocytopenia, has been reported. Pancytopenia and neutropenia have also been reported.


Dermatologic side effects have included rare reports of alopecia and angioedema. Rash, pruritus, urticaria, and flushing have also been reported.


No evidence of hypersensitivity (eosinophilia, rash, leukocytosis) accompanied the rare reports of drug fever. The fever may have been idiosyncratic or evidence of a reaction to drug-induced tissue necrosis in hydatid cysts.

Other side effects have included chills and drug fever.

Nervous system

Nervous system side effects have been reported rarely. These have included weakness, drowsiness, and seizures.

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