Minor ailments

Pinworms and threadworms

Clinical basis & sources

Sources used

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Allowable drugs under Schedule 4 (2)

Drugs an Ontario pharmacist may prescribe for Pinworms and threadworms under O. Reg. 256/24, Schedule 4. Choice still depends on the assessment, contraindications, allergies, and product availability — this is the eligible list, not a recommendation.

  • Mebendazole
  • Pyrantel pamoate

Symptoms this assessment screens

  • Nocturnal perianal itching or pruritus ani
  • Small white thread-like worms seen or close household/daycare exposure reported
  • Tape test or paddle test positive or appropriate if confirmation is needed
  • Age and weight are suitable for selected therapy and exact dose can be calculated
  • Household/caregiver treatment and hygiene plan can be implemented

Red flags — any positive means refer

  • Age under 2 years, pregnancy, breastfeeding, immunocompromise, complex medical illness, or medication safety uncertainty
  • Severe abdominal pain, persistent vomiting, fever, weight loss, blood in stool, marked diarrhea, or significant systemic illness
  • Worms look unlike small white threadworms, tapeworm segments suspected, recent travel/exposure suggests another parasite, or diagnosis is uncertain
  • Perianal skin infection, cellulitis, severe excoriation, vaginal itching/discharge, urinary symptoms, or pelvic pain
  • Persistent or recurrent symptoms after two correctly timed doses plus household hygiene measures
  • School, daycare, long-term care, or other institutional outbreak concern

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