Antihistamine (also used as anti-nausea and sedative)
Last reviewed June 2026
Who is this for?
Promethazine is an antihistamine that works by blocking a natural substance called histamine in your body. It helps reduce allergic reactions, prevents nausea and vomiting, and can make you feel sleepy, which is why it is sometimes used to help with sleep or calm you down before surgery.
Blocks H1 histamine receptors and muscarinic cholinergic receptors, suppressing allergic responses, nausea, and emesis while producing sedation through central nervous system depression.
Prescription Required
You need a doctor's prescription to buy this drug.
Explore this drug
For allergies: Take one 25 mg tablet at bedtime, or 10-25 mg two to three times daily. For motion sickness: Take 25 mg about 30 minutes to 1 hour before travelling, and repeat every 8-12 hours if needed. For nausea and vomiting: Take 12.5-25 mg every 4-6 hours as needed. You can take it with food to reduce stomach upset. This drug makes you very drowsy, so take it at night if you only need one dose a day.
If you miss a dose, take it as soon as you remember. But if it is almost time for your next dose, just skip the missed one and continue as normal. Do not take a double dose to make up for the one you missed.
This drug is commonly abused in Nigeria when mixed with codeine cough syrup — do not use it to get high, it is very dangerous and can kill. Do not buy from roadside sellers or unregistered vendors as fake versions are common. Because it causes heavy drowsiness, do not drive okada, keke, or any vehicle after taking it.
Alcohol: Do not drink alcohol while taking promethazine — it makes the drowsiness much worse and can be dangerous. Tramadol and codeine: Taking promethazine with these painkillers increases the risk of extreme drowsiness, slow breathing, and even death. Other sleeping pills or sedatives (like diazepam): Combining them with promethazine can cause dangerously deep sleep.
Check your specific combination
Is it safe to take Promethazine with your other drugs?
Promethazine is not recommended during pregnancy, especially in the last trimester, and should be avoided while breastfeeding unless your doctor specifically prescribes it — always consult your doctor first.
Store in a cool, dry place away from direct sunlight and heat — Nigerian weather can spoil medicines quickly. Do not store in the bathroom where there is humidity. Keep the bottle or pack tightly closed and always keep it far out of reach of children.
For information only — not medical advice. Always talk to a doctor or pharmacist before changing your medication.
Names this drug is sold under — especially in Nigerian and West African pharmacies
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Counterfeit Drug Warning
Fake drugs are a serious problem in Nigeria. Always buy from a registered pharmacy. If the packaging looks different from what is described above, do not use it.
Dispensing Promethazine Hydrochloride?
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