Skip to main content

Vermox Side Effects

Generic name: mebendazole

Medically reviewed by Last updated on Mar 24, 2022.

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.

For the Consumer

Applies to mebendazole: oral tablet chewable

Side effects requiring immediate medical attention

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 immediately if any of the following side effects occur while taking mebendazole:


  • Black, tarry stools
  • chills
  • convulsions
  • cough or hoarseness
  • dark urine
  • fever with or without chills
  • general feeling of tiredness or weakness
  • hives or welts, itching, or skin rash
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • light-colored stools
  • lower back or side pain
  • nausea and vomiting
  • painful or difficult urination
  • pale skin
  • redness of the skin
  • sore throat
  • sores, ulcers, or white spots on the lips or in the mouth
  • unusual bleeding or bruising
  • unusual tiredness or weakness
  • upper right abdominal or stomach pain
  • yellow eyes and skin

Incidence not known

  • Blistering, peeling, or loosening of the skin
  • diarrhea
  • difficulty with swallowing
  • dizziness
  • fast heartbeat
  • joint or muscle pain
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • tightness in the chest

Side effects not requiring immediate medical attention

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:


  • Abdominal or stomach pain or upset

Incidence not known

  • Bloated
  • excess air or gas in the stomach or intestines
  • full feeling
  • hair loss or thinning of the hair
  • loss of appetite
  • passing gas
  • weight loss

For Healthcare Professionals

Applies to mebendazole: compounding powder, oral tablet chewable


At the recommended dose, this drug was generally well tolerated; however, patients with high parasitic burdens reported diarrhea and abdominal pain.[Ref]


Common (1% to 10%): Abdominal pain

Uncommon (0.1% to 1%): Abdominal discomfort, diarrhea, flatulence

Frequency not reported: Nausea, vomiting[Ref]


Rare (0.01% to 0.1%): Rash

Frequency not reported: Pruritus

Postmarketing reports: Toxic epidermal necrolysis, Stevens-Johnson syndrome, exanthema, alopecia, angioedema, urticaria[Ref]


Frequency not reported: Anorexia[Ref]


Frequency not reported: Transient changes in liver function tests, granulomatous hepatitis

Postmarketing reports: Hepatitis, abnormal liver function tests[Ref]


Frequency not reported: Profound leukopenia, anemia, thrombocytopenia, pancytopenia

Postmarketing reports: Agranulocytosis, neutropenia[Ref]

Nervous system

Frequency not reported: Weakness, drowsiness

Postmarketing reports: Convulsions/seizures, dizziness[Ref]


Postmarketing reports: Glomerulonephritis[Ref]


Frequency not reported: Chills, drug fever, flushing[Ref]


Postmarketing reports: Hypersensitivity (including anaphylactic reaction, anaphylactoid reaction)[Ref]


1. Barrett-Connor E "Drugs for the treatment of parasitic infection." Med Clin North Am 66 (1982): 245-55

2. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

3. Miskovitz PF, Javitt NB "Leukopenia associated with mebendazole therapy of hydatid disease." Am J Trop Med Hyg 29 (1980): 1356-8

4. Kammerer WS, Schantz PM "Long term follow-up of human hydatid disease (echinococcus granulosus) treated with a high-dose mebendazole regimen." Am J Trop Med Hyg 33 (1984): 132-7

5. Bekhti A, Pirotte J "Hepatotoxicity of mebendazole: relationship with serum concentrations of the drug." Gastroenterol Clin Biol 11 (1987): 701-3

6. Witassek F, Bircher "Chemotherapy of larval echinococcosis with mebendazole: microsomal liver function and cholestasis as determinants of plasma drug level." Eur J Clin Pharmacol 25 (1983): 85-90

7. "Product Information. Vermox (mebendazole)." Janssen Pharmaceutica, Titusville, NJ.

8. Cerner Multum, Inc. "Australian Product Information." O 0

9. Braithwaite PA, Thomas RJ, Thompson RC "Hydatid disease, the alveolar variety in australia: a case report with comment on the toxicity of mebendazole." Aust N Z J Surg 55 (1985): 519-23

10. Colle I, Naegels S, Hoorens A, Hautekeete M "Granulomatous hepatitis due to mebendazole." J Clin Gastroenterol 28 (1999): 44-5

11. Levin MH, Weinstein RA, Axelrod JL, Schantz PM "Severe, reversible neutropenia during high-dose mebendazole therapy for echinococcosis." JAMA 249 (1983): 2929-31

12. Fernandez-Banares F, Gonzalez-Huix F, Xiol X, et al "Marrow aplasia during high dose mebendazole treatment." Am J Trop Med Hyg 35 (1986): 350-1

13. Murray-Lyon IM, Reynolds KW "Complication of mebendazole treatment for hydatid disease." Br Med J 2 (1979): 1111-2

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.