Key Facts
- Drug Class
- First-generation antihistamine (phenothiazine derivative)
- Prescription
- Over the counter
- NAFDAC Status
- NAFDAC Registered
- Forms
- Tablet, Syrup, Injection
- Price Range
- ₦200 - ₦4,000
What is Promethazine?
Promethazine is one of the most versatile and widely used medications in Nigeria, functioning as an antihistamine, anti-nausea agent, cough suppressant, and sedative all in one. It belongs to the phenothiazine class of first-generation antihistamines and works by blocking histamine H1 receptors throughout the body, which is responsible for its anti-allergy effects. Unlike newer second-generation antihistamines such as cetirizine and loratadine, promethazine readily crosses the blood-brain barrier, which accounts for its pronounced sedative effect. This sedation, while considered a side effect in many contexts, is actually one of the primary reasons promethazine is so popular in Nigeria — it is frequently used as a sleep aid and calming agent. Best known by its brand names Phenergan and Avomine, promethazine is stocked in virtually every pharmacy and patent medicine store from the busy Idumota market area in Lagos to neighbourhood chemists in Enugu, Kaduna, and Maiduguri.
In Nigeria, promethazine occupies a unique position in everyday healthcare. It is a key ingredient in many popular cough syrups sold across the country, where it serves as both a cough suppressant and antihistamine to reduce the runny nose and sneezing that accompany upper respiratory infections. Promethazine cough syrups — often combined with other active ingredients such as dextromethorphan or pseudoephedrine — are among the most frequently purchased over-the-counter medications in Nigerian pharmacies. The drug is also widely used for nausea and vomiting, making it invaluable for pregnant women suffering from morning sickness (though use requires medical supervision) and for travellers preparing for Nigeria's notoriously long and often bumpy road journeys between cities like Lagos and Abuja, Benin and Onitsha, or Kano and Jos. Avomine, the Sanofi brand marketed specifically for travel sickness, is a trusted companion for many Nigerian travellers.
Despite its widespread legitimate use, promethazine has also been at the centre of substance abuse concerns in Nigeria. Codeine-promethazine cough syrups became a major public health issue, with young Nigerians mixing these syrups into drinks for their euphoric and sedative effects. This crisis led to NAFDAC banning the sale of codeine-containing cough syrups in pharmacies and patent medicine stores in 2018, restricting them to hospitals only. While promethazine alone does not produce the same euphoric effects as codeine, it is still sometimes misused for its strong sedative properties. Promethazine is available in Nigeria as tablets (10mg and 25mg), oral syrup (5mg/5ml), and injection for hospital use. It remains an over-the-counter medication when sold in tablet and syrup form without codeine, and it continues to be an important and effective medication when used responsibly for its intended purposes.
What is Promethazine used for?
In Nigeria, Promethazine is commonly used for:
- Allergic conditions — hay fever, allergic rhinitis, urticaria (hives), itching, and other allergic reactions where an antihistamine with sedative properties may be beneficial
- Nausea and vomiting — effective for motion sickness, morning sickness in pregnancy (with medical supervision), post-operative nausea, and drug-induced nausea
- Cough suppression — as a component of cough syrup formulations, promethazine reduces cough reflex and manages associated allergic symptoms like runny nose and sneezing
- Sedation and sleep aid — used short-term for insomnia and anxiety-related sleep difficulties, and as a pre-operative or pre-procedural sedative in hospitals
- Motion sickness prevention — taken before long journeys to prevent nausea, vomiting, and dizziness associated with road, sea, or air travel
- Adjunct to pain management — sometimes used alongside analgesics in hospital settings to enhance pain relief and reduce nausea from opioid pain medications
Dosage
IMPORTANT
Always follow your doctor's or pharmacist's instructions. The information below is for general reference only.
Adults
For allergies (rhinitis, urticaria, itching): 25mg at bedtime, or 10mg to 25mg two to three times daily. Due to drowsiness, bedtime dosing is often preferred. For nausea and vomiting: 25mg at onset, then 10mg to 25mg every four to six hours as needed. For motion sickness prevention: 25mg taken the night before travel, then 25mg on the morning of travel. For long journeys, an additional 25mg may be taken after six to eight hours. As a short-term sleep aid: 25mg to 50mg taken 30 minutes to one hour before bedtime. For cough: Follow the dosage instructions on the specific cough syrup formulation being used, as the concentration of promethazine varies between products.
Children
Children aged 5 to 10 years: 10mg to 25mg daily in divided doses for allergies, or a single dose of 10mg to 25mg at bedtime. Children aged 2 to 5 years: 5mg to 15mg daily in divided doses, or as directed by a doctor. Promethazine syrup (5mg/5ml) is the preferred formulation for children. IMPORTANT: Promethazine should NOT be used in children under 2 years of age due to the risk of fatal respiratory depression. Always use the measuring device provided with the syrup — never estimate doses with household spoons. Consult a doctor or pharmacist for appropriate paediatric dosing.
Elderly
Elderly patients are more sensitive to the sedative and anticholinergic effects of promethazine. Start with the lowest effective dose, typically 10mg to 25mg once daily, preferably at bedtime. Monitor for excessive drowsiness, confusion, dizziness, and falls. Promethazine may worsen urinary retention in elderly men with prostate enlargement and may increase the risk of constipation.
Promethazine causes significant drowsiness in most people. Do not drive, operate machinery, or perform tasks requiring alertness after taking promethazine. The sedative effect is enhanced by alcohol — avoid alcohol completely while using promethazine. Take motion sickness doses at least 30 minutes to one hour before travel for best effect. If using promethazine as a sleep aid, allow at least eight hours for sleep to avoid morning grogginess. Promethazine tablets should be swallowed whole with water and can be taken with or without food, though taking them with food may reduce stomach upset.
Side Effects
Common side effects
- •Drowsiness and sedation — the most prominent side effect, experienced by the majority of users. Can persist into the following day as a 'hangover' effect.
- •Dry mouth — caused by the anticholinergic properties of promethazine
- •Dizziness and lightheadedness, especially when standing up quickly
- •Blurred vision
- •Constipation
- •Difficulty passing urine (urinary hesitancy)
Serious side effects — seek medical help immediately
- Severe respiratory depression — particularly dangerous in children under 2 years of age and can be fatal. This is why promethazine is contraindicated in this age group.
- Neuroleptic malignant syndrome — a rare but potentially fatal reaction characterised by high fever, muscle rigidity, confusion, and rapid heartbeat
- Severe low blood pressure (hypotension) — particularly with injectable forms or when combined with other sedating medications
- Seizures — rare, but promethazine can lower the seizure threshold in susceptible individuals
- Blood disorders — very rare cases of agranulocytosis (dangerously low white blood cell count) and thrombocytopenia (low platelet count)
- Severe allergic reaction — paradoxical allergic reaction to promethazine itself, including skin rash, swelling, and difficulty breathing
When to see a doctor
Seek immediate medical attention if you or your child experiences difficulty breathing, unusually slow or shallow breathing, severe drowsiness that you cannot be woken from, high fever with muscle stiffness and confusion, seizures, or signs of a severe allergic reaction such as facial swelling or difficulty breathing. See a doctor if you experience persistent confusion, hallucinations, severe constipation, inability to pass urine, or irregular heartbeat. In Nigeria, the emergency departments of teaching hospitals and general hospitals can manage these serious reactions. If a child under 2 years accidentally takes promethazine, treat it as a medical emergency and go to the nearest hospital immediately.
Warnings & Precautions
Do not take Promethazine if you have:
- Do NOT use in children under 2 years of age — risk of fatal respiratory depression
- Do not use if you have a known allergy to promethazine or other phenothiazine medications
- Do not use if you have severe liver disease — promethazine is metabolised by the liver and can accumulate to toxic levels
- Use with extreme caution in patients with epilepsy — promethazine can lower the seizure threshold
- Do not use in patients who are deeply sedated, in a coma, or who have central nervous system depression from any cause
Drug interactions
- •Alcohol — significantly enhances the sedative effect of promethazine, potentially causing dangerous levels of drowsiness, respiratory depression, and loss of consciousness. Avoid all alcohol including beer, palm wine, and ogogoro.
- •Other sedating medications (sleeping pills, benzodiazepines, opioids, other antihistamines) — additive sedation can lead to excessive drowsiness and respiratory depression. This combination is particularly dangerous.
- •Codeine and other opioids — promethazine enhances the sedative and respiratory depressant effects of opioids. This combination was the basis of the codeine-promethazine cough syrup abuse crisis in Nigeria.
- •Anticholinergic drugs (e.g., hyoscine, some antidepressants) — increased risk of dry mouth, constipation, urinary retention, blurred vision, and confusion
- •Blood pressure medications — promethazine can cause low blood pressure, which may be worsened by antihypertensive drugs
- •Monoamine oxidase inhibitors (MAOIs) — can prolong and intensify the anticholinergic and sedative effects of promethazine
Pregnancy & Breastfeeding
Promethazine has a long history of use in pregnancy for the management of nausea and vomiting (morning sickness and hyperemesis gravidarum), and it is considered relatively safe when used under medical supervision. It is sometimes given in Nigerian hospitals to pregnant women with severe vomiting that does not respond to simpler measures. However, it should be used at the lowest effective dose and for the shortest possible time, particularly in the first trimester. Promethazine used near the time of delivery may cause sedation and respiratory depression in the newborn. Promethazine passes into breast milk and can cause drowsiness and other side effects in the breastfed infant. If you are breastfeeding, consult your doctor before taking promethazine. If use is necessary, the lowest effective dose should be used and the baby should be monitored for excessive sleepiness, feeding difficulties, and irritability.
Brands of Promethazine in Nigeria
4 brands available in Nigeria.
| Brand Name | Manufacturer | Strength | Form | NAFDAC Reg. No. |
|---|---|---|---|---|
| Phenergan | Sanofi | 10mg, 25mg, 5mg/5ml | Tablet/Syrup | |
| Avomine | Sanofi | 25mg | Tablet | |
| Promethazine | Various (Generic) | 10mg, 25mg | Tablet | A11-100020 |
| M&B Promethazine | May & Baker | 10mg, 25mg, 5mg/5ml | Tablet/Syrup |
How to Verify Your Promethazine is Genuine
- 1Check for a valid NAFDAC registration number on the packaging — all genuine promethazine products sold in Nigeria must be registered with NAFDAC.
- 2Verify the NAFDAC registration number using the NAFDAC Green Book online portal or the NAFDAC mobile verification app available for Android and iOS devices.
- 3Purchase from licensed pharmacies and registered patent medicine stores only. Avoid buying promethazine products from unregistered vendors, roadside sellers, or unlicensed online platforms.
- 4For branded products like Phenergan and Avomine, check that the packaging matches the manufacturer's official design, including the Sanofi logo, colour scheme, and overall packaging quality.
- 5Inspect the packaging for clear, professional printing with correct spelling, a visible batch number, manufacturing date, and expiry date. Blurred printing, misspellings, or missing information suggest a counterfeit product.
- 6Be wary of promethazine cough syrups sold without proper labelling, particularly those claiming to contain codeine — the sale of codeine-containing cough syrups is restricted by NAFDAC to hospitals only.
Promethazine Price in Nigeria
Promethazine prices in Nigeria typically range from ₦200 to ₦4,000 per pack, depending on the brand, strength, and where you buy it.
₦200 – ₦4,000
per pack
Prices vary by location and vendor. Last updated: 2026-02-01
Where to Buy
Purchase Promethazine only from licensed pharmacies and verified distributors. Avoid buying medicines from unverified sources, roadside vendors, or unregistered market stalls.
Frequently Asked Questions
Sources
- •NAFDAC Greenbook — National Agency for Food and Drug Administration and Control registered products database
- •WHO Model List of Essential Medicines (23rd List, 2023)
- •British National Formulary (BNF)
- •Nigerian Standard Treatment Guidelines