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What the label lists and what reports show

Mebendazole side effects

Mebendazole's FDA label lists its adverse reactions in its own words. FAERS holds 784 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is nausea (50 reports).

  • No generic listed

Check it at the source: the mebendazole FDA label on DailyMed (effective October 5, 2021, Janssen Pharmaceuticals, Inc.); the FDA FAERS public dashboard.

What does the label list?

From the label: adverse reactions

Adverse reactions reported in clinical trials were anorexia, abdominal pain, diarrhea, flatulence, nausea, vomiting and rash. ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Janssen Pharmaceuticals, Inc. at 1-800-JANSSEN (1-800-526-7736) or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Studies Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. The safety of mebendazole was evaluated in 6276 adult and pediatric subjects one year of age and older who participated in 39 clinical trials for treatment of single or mixed parasitic infections of the gastrointestinal tract. In these trials, the formulations, dosages and duration of mebendazole treatment varied. …

Source: FDA drug label, Janssen Pharmaceuticals, Inc., effective October 5, 2021 (SPL set a720c424-517a-461b-8e13-6c37caf8aa3f), via openFDA; the full label on DailyMed

What do FAERS reports show?

784 reports list mebendazole among the medicines taken, each a report of something that happened, not proof the medicine caused it; 56 are coded as a death and 185 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 19 reactions below, 5 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.

Reports received each year

The 25 most reported reactions

  • Foetal Exposure During Pregnancy (a use or a product term, not a reaction)57
  • Nausea (named in the label)50
  • Abdominal Pain (named in the label)44
  • Drug Ineffective (a use or a product term, not a reaction)44
  • Vomiting (named in the label)44
  • Off Label Use (a use or a product term, not a reaction)43
  • Dizziness (named in the label)37
  • Fatigue34
  • Diarrhoea (named in the label)32
  • Drug Exposure During Pregnancy (a use or a product term, not a reaction)30
  • Headache30
  • Asthenia29
  • Pyrexia29
  • Pruritus24
  • Exposure During Pregnancy (a use or a product term, not a reaction)22
  • Malaise22
  • Abortion Spontaneous21
  • Anxiety20
  • Pain19
  • Abdominal Pain Upper18
  • Intentional Self-Injury18
  • Hallucination17
  • Back Pain16
  • Decreased Appetite16
  • Drug Interaction (a use or a product term, not a reaction)16

Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms

What next?

Mebendazole: the full record
label, generics, price, shortages, recalls
Side effects hub
the most reported medicines and reactions