Nausea and vomiting of pregnancy
Clinical basis & sources
- Primary source
- OCP Minor Ailments Prescribing
Sources used
- Ontario Regulation 256/24: GeneralGovernment of Ontario · 2026
- Minor Ailments: Drug Classes and Specified DrugsOntario College of Pharmacists · 2026
- Executive Officer Notice: Update to Funding for Minor Ailment Services in Ontario Pharmacies (Effective July 1, 2026)Government of Ontario · 2026-05-19
- Morning Sickness: Nausea and Vomiting of PregnancyAmerican College of Obstetricians and Gynecologists · 2026
- Diclectin Product MonographHealth Canada Drug Product Database · 2026-05
- Doxylamine succinate-pyridoxine hydrochloride (Diclegis/Diclectin) Fact SheetMotherToBaby / NCBI Bookshelf · 2024
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Allowable drugs under Schedule 4 (5)
Drugs an Ontario pharmacist may prescribe for Nausea and vomiting of pregnancy 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.
- Dimenhydrinate
- Diphenhydramine
- Doxylamine
- Promethazine
- Pyridoxine
Symptoms this assessment screens
- Pregnancy is confirmed and patient has or is arranging prenatal care
- Symptoms are consistent with typical early pregnancy nausea/vomiting
- Able to keep some fluids down and urination is not markedly reduced
- No vaginal bleeding, pelvic pain, severe abdominal pain, fever, or hypertensive-disorder symptoms
- Medication, supplement, alcohol/cannabis, allergy, and sedation-risk review completed
- Diet, hydration, trigger management, and conservative measures discussed
Red flags — any positive means refer
- Unable to keep fluids down, very low urine output, dizziness/fainting, confusion, ketone concern, electrolyte concern, or weight loss
- Vaginal bleeding, pelvic pain, severe abdominal pain, fever, bloody diarrhea, or persistent/worsening vomiting outside the typical early-pregnancy pattern
- Severe headache, visual symptoms, right-upper-quadrant pain, chest pain, shortness of breath, palpitations, syncope, weakness, or neurologic symptoms
- Diabetes, thyroid disease, renal disease, eating disorder, severe mental-health concern, multiple pregnancy/molar pregnancy concern, or other high-risk pregnancy/medical condition
- Doxylamine/diphenhydramine/dimenhydrinate/promethazine allergy, MAO inhibitor use, severe anticholinergic risk, unsafe sedation risk, or interacting medicines that cannot be managed
- No improvement after initial therapy, escalating dose needs, inability to work/function, or patient requests medicines outside Ontario Schedule 4
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