Most advice about Phenergan and alcohol focuses on what happens if you take your dose and then have a drink later. But the question can work the other way too. If you have already been drinking and are wondering whether you can take promethazine, the same interaction applies, just in the opposite order.
Promethazine is a sedating antihistamine, while alcohol is a central nervous system depressant. Taking one while the other is still affecting you can increase the overall sedating effect. This can happen whether alcohol or promethazine is taken first.
This guide looks at the timing question directly: how long should you wait before taking promethazine after drinking, can you take Phenergan after alcohol, and what can you do instead if you are looking for help getting to sleep after a night out?
Key things to know about side effects
- Taking promethazine while alcohol is still affecting you can increase drowsiness and sedation, just as drinking alcohol after taking promethazine can
- There is no published minimum number of hours that guarantees it is safe to take promethazine after drinking
- The NHS estimates that the body processes roughly one unit of alcohol per hour, although this varies from person to person
- Promethazine should not be used to help you sleep after drinking or to try to counter the effects of alcohol
Why Timing Works Both Ways
The interaction between promethazine and alcohol is not limited to taking the tablet first. Both substances can slow activity in the central nervous system, so their sedating effects may add together regardless of which one you take first.
For example, taking a 25mg promethazine tablet after drinking can increase sedation in the same way that drinking alcohol after taking promethazine can. This is particularly important if you are already feeling sleepy or affected by alcohol.
How Long Does Alcohol Stay in Your System?
Alcohol is mainly broken down by the liver. NHS guidance says that the body typically processes around one unit of alcohol per hour, but this is only a rough estimate. The rate can vary between people and can be affected by factors such as body size, sex, liver function, food intake and how much alcohol you have consumed.
A single drink may take a few hours to leave your system, while a heavier drinking session can mean that alcohol remains in your body for much longer. You may also still be affected by alcohol even when you feel more alert or less drunk.
How Long Should You Wait to Take Promethazine After Drinking?
There is no officially published minimum waiting time between drinking alcohol and taking promethazine. There is also no specific number of hours that can guarantee the combination is safe for everyone.
The important point is to avoid taking promethazine while alcohol is still affecting you. As a practical approach, wait until the intoxicating and sedating effects of alcohol have completely worn off. After heavier drinking, this may take considerably longer than after a single drink.
If you are unsure, the more cautious option is to skip that dose and speak to a pharmacist. This is especially important if you are thinking about taking promethazine for its short term licensed use for insomnia after drinking.
Can You Take Phenergan After Drinking Alcohol?
It is best to avoid taking Phenergan while alcohol is still affecting you. Taking Phenergan shortly after drinking can combine two substances that cause sedation. This may increase drowsiness, poor coordination, impaired judgement, confusion, memory problems and low blood pressure (hypotension).
The risk may be greater after heavier drinking or if you are also taking other medicines that cause drowsiness. The same concern applies to both Phenergan 25mg tablets and the elixir.
If You Feel You Need Something After a Night of Drinking
It can be tempting to take a sedating antihistamine to help you sleep after drinking. However, promethazine is not intended to counter the effects of alcohol, and taking it while alcohol is still affecting you can increase sedation.
For now, simple steps such as drinking water, having something to eat if you can and giving your body time to process the alcohol may be more appropriate. Avoid taking other medicines simply to make yourself sleep while you are still affected by alcohol.
If you still have sleep problems after the alcohol has completely worn off, speak to a pharmacist about whether promethazine is suitable for you. If it has been recommended for short term insomnia, follow the directions you have been given rather than using it as a way to extend or manage a night of drinking.
Who Should Be Extra Cautious About Central Nervous System Effects
- Anyone who has been drinking heavily, as it can take considerably longer for the alcohol to leave the body
- Older adults, who may be more sensitive to the sedating effects of alcohol and promethazine
- Anyone taking other medicines that cause drowsiness, including sleeping tablets, opioid painkillers such as codeine or benzodiazepines. Other medicines or recreational drugs that cause sedation may also increase the risk
- Anyone with liver or breathing problems, who may need extra advice before using promethazine or drinking alcohol
Who Should Not Take Promethazine with Other Medicines
Whether promethazine is suitable for you depends on your individual circumstances and any other medicines you take. The following is general safety information and does not replace advice from a pharmacist or prescriber.
| Contraindication | Detail |
|---|---|
| Known hypersensitivity | Do not take promethazine if you are allergic to promethazine or other phenothiazine medicines, as this could cause an allergic reaction |
| Children under 6 years | Promethazine is contraindicated in this age group |
| Coma or CNS depression | Promethazine should not be used in people with significant central nervous system depression, including significant alcohol intoxication |
| MAOIs | Promethazine should not be taken with MAOIs or within 14 days of stopping them |
| Use beyond 7 days | Short term insomnia treatment should not continue beyond 7 days without medical advice |
Other conditions, including epilepsy, liver or kidney problems, Parkinson's disease, glaucoma, prostate enlargement and some heart conditions associated with QT prolongation, may require extra caution rather than being an outright contraindication.
Seek urgent medical help if you develop signs of a severe allergic reaction or other serious symptoms. Speak to a pharmacist, prescriber or doctor if any of these conditions apply to you, or if you regularly drink alcohol and are considering taking promethazine. Make sure you tell them about your medical conditions and any medicines you take.
Phenergan Tablets and Elixir: Your Options
EverydayMeds supplies branded Phenergan in two formats. Both require the same short online safety check before purchase. Both are pharmacy (P) medicines rather than prescription only medicines, so a GP referral is not normally needed.
| Product | Strength | Pack size | Price |
|---|---|---|---|
| Phenergan Tablets | 25mg promethazine hydrochloride | 56 tablets | £14.99 |
| Phenergan Elixir | 5mg in 5ml oral solution | 100ml | £14.49 |
Phenergan Elixir is the liquid version, so follow the storage instructions on the product packaging. Prices shown are EverydayMeds' standard listed prices at the time of writing and can change. Check the current product page before ordering.
Medical Disclaimer
This article is provided for general information only and does not constitute medical advice. It is not a substitute for advice from a qualified healthcare professional. Promethazine should be used according to appropriate pharmacist or prescriber guidance, and whether it is suitable for you depends on your individual circumstances.
If you have questions about taking any medicine with alcohol, speak to a pharmacist, GP or doctor, particularly if you take antihistamines or other medicines that can cause drowsiness.
If you develop severe symptoms, seek urgent medical help. Call 999 or go to your nearest A&E in an emergency.
