Avomine
Avomine (Promethazine theoclate 25 mg) — sedating H1 antihistamine + anticholinergic for motion sickness, vestibular vertigo, and Meniere’s acute attacks.
✓ Medically reviewed by Morgan Ellis — Pharmacy Researcher · 8 years experience · Last reviewed: May 2026
⚡ Quick Answer — What is Avomine?
Avomine contains promethazine theoclate 25 mg, a first-generation H1 antihistamine with antiemetic, anticholinergic, and sedative properties. It is the established first-line agent for motion sickness, vestibular nausea, and vertigo, and is also used for sedation and as an adjunct in allergy and pregnancy-related nausea (jurisdiction-dependent). Take 30–60 minutes before travel for motion-sickness prophylaxis. Manufactured by Wockhardt under WHO-GMP standards.
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When promethazine is the right antiemetic
Promethazine is the go-to drug for motion sickness — sea, air, car, and amusement-park motion. It is also effective for vestibular vertigo (acute labyrinthitis, vestibular neuritis, Meniere’s acute attacks), and as a sedating adjunct in allergic reactions or anxiety-related nausea. It is not first-line for chemotherapy-induced nausea (use ondansetron/granisetron instead) and not first-line for nausea-vomiting of pregnancy in most modern guidelines (NVP first-line is doxylamine+B6 — Doxinate, Pregnidoxin NU). Some jurisdictions still use promethazine for hyperemesis gravidarum after first-line failure.
Why order from MedsBase
Avomine is supplied from a WHO-GMP certified manufacturer. Every order ships discreetly worldwide and is covered by our Reshipment Assurance Policy — if it does not arrive within 20 business days, we reship at no cost. Promethazine has been the global standard for motion sickness for decades and remains a useful sedating antiemetic when histaminergic/cholinergic vestibular nausea is the dominant problem.
Mechanism of action
Promethazine is a phenothiazine-derived antihistamine. It blocks H1 histamine receptors (the antihistamine effect that reduces motion-induced vestibular signalling and gives sedation), muscarinic acetylcholine receptors (the anticholinergic effect that further suppresses vestibular and gut motility-driven emesis), and D2 dopamine receptors (a mild antiemetic effect at the chemoreceptor trigger zone). The unique value of promethazine in motion sickness is the combined H1 + anticholinergic blockade — the vestibular system depends on both pathways. The same combined blockade also explains its strong sedative and dry-mouth profile.
Indications
- Motion sickness: sea, air, car, train; especially when other agents (cinnarizine, hyoscine patch) have failed or are unavailable.
- Vestibular vertigo: acute labyrinthitis, vestibular neuritis, Meniere’s acute attacks.
- Allergic reactions (urticaria, hay fever) where sedation is helpful or non-sedating antihistamines have failed.
- Pre-medication for anaesthesia (sedation + antiemetic + drying of secretions).
- Insomnia short-term occasional use.
- Hyperemesis gravidarum (jurisdiction-dependent, after first-line doxylamine+B6 failure).
Dose
| Indication | Dose |
|---|---|
| Motion sickness (adult) | 25 mg the night before, repeat 25 mg morning of travel; or 25 mg 1–2 h pre-travel; max 75 mg/day |
| Vestibular vertigo (adult) | 25 mg every 8–12 h during acute episode; taper after 2–3 days (long-term use slows vestibular compensation) |
| Children 5–10 y | 12.5 mg the night before travel and again the morning of travel |
| Children 2–5 y | Use only if essential under medical supervision; 6.25 mg twice daily maximum |
| Children < 2 y | CONTRAINDICATED — risk of fatal respiratory depression |
| Older adults (> 65) | Use cautiously — high anticholinergic burden; risk of confusion, falls, urinary retention |
Side effects
- Very common: sedation, dry mouth, blurred vision, urinary hesitancy, constipation
- Common: dizziness, hypotension on standing, palpitation, mild confusion (especially older adults)
- Less common: photosensitivity, rash, paradoxical excitation in children, extrapyramidal reactions (low frequency vs other phenothiazines)
- Rare but serious: agranulocytosis, neuroleptic malignant syndrome (very rare), severe respiratory depression in young children, seizures in overdose
Drug interactions
- CNS depressants (alcohol, opioids, benzodiazepines, gabapentinoids, sleep medication): additive sedation and respiratory depression — avoid combination.
- Anticholinergics (TCAs, oxybutynin, atropine, hyoscine patch, antipsychotics): additive dry mouth, urinary retention, cognitive impairment — especially in older adults.
- MAO inhibitors: may prolong and intensify sedation — avoid combination.
- Adrenaline (epinephrine): promethazine may reverse the pressor effect (use noradrenaline if vasopressor needed during anaphylaxis on promethazine).
- Pregnancy test interference: may cause false positive/negative immunological pregnancy tests.
Frequently Asked Questions
How long before travel should I take Avomine?
For best motion-sickness protection, take 25 mg the night before travel and a second 25 mg dose 1–2 hours before departure. Once the journey is underway and you are already nauseated, prevention is much harder — take the dose proactively.
Will Avomine make me sleepy?
Yes — pronounced drowsiness is the dominant side effect. Do not drive, fly an aircraft, scuba dive, or operate machinery for 24 hours after a dose. Many users find this useful for long-haul flights but it is dangerous before active tasks.
Can Avomine be used in pregnancy?
Promethazine has been used historically for hyperemesis gravidarum but is no longer first-line in most modern guidelines. First-line for nausea-vomiting of pregnancy (NVP) is doxylamine + B6 (Doxinate, Pregnidoxin NU); ondansetron, metoclopramide, and promethazine are reserved for refractory cases under specialist supervision.
Can children take Avomine?
Children under 2 years must NOT take promethazine — risk of fatal respiratory depression. For ages 2–5 use only if essential under medical supervision. Standard motion-sickness dosing starts from age 5 with 12.5 mg the night before and morning of travel.
What is the difference between Avomine and ondansetron?
Avomine is a sedating H1 antihistamine + anticholinergic — ideal for motion sickness and vestibular vertigo where the histaminergic and cholinergic pathways are dominant. Ondansetron is a 5-HT3 antagonist — ideal for chemo, radiation, surgery, severe gastroenteritis where the serotonin pathway is dominant. They are not interchangeable.
Is Avomine addictive?
No, promethazine is not a controlled substance and does not cause physical dependence. However, the strong sedation makes it occasionally misused for sleep or to potentiate opioids — the latter is dangerous because of respiratory depression.
Can I drink alcohol with Avomine?
No — combination causes profound sedation and respiratory depression. Avoid alcohol, sleeping pills, and opioids while on promethazine.
What if I forget a dose?
Promethazine is usually used for prevention — take the next dose at the next planned time. If you miss the pre-travel dose, taking it once travel-induced nausea has already started is less effective; an ODT 5-HT3 (Ondem MD) or a cinnarizine alternative may give better breakthrough control.
How does Avomine differ from cinnarizine and meclozine?
All three are anti-vertigo/motion-sickness antihistamines. Cinnarizine has additional calcium-channel blocking action (useful in Meniere’s) and is less sedating. Meclozine is intermediate — less sedating than promethazine, longer-acting than cinnarizine. Promethazine is the most strongly sedating and is preferred when sedation is a benefit (long flights, severe vertigo).
How is Avomine stored?
Store tablets at room temperature (below 25°C), protected from light and moisture. Keep out of reach of children — accidental paediatric ingestion can cause severe respiratory depression.
Other Nausea Treatments
- Stemetil MD (prochlorperazine — vestibular nausea ODT)
- Dompewal (domperidone — gastric-emptying nausea)
- Ondem (ondansetron — chemo/PONV)
- Doxinate (doxylamine + B6 — pregnancy nausea)
- Metopar (paracetamol + metoclopramide — migraine nausea)
- Browse all Nausea Treatments
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| Strength | 25 mg |
|---|---|
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