Promethazine, whether taken as branded Phenergan or another medicine containing promethazine hydrochloride, is a sedating antihistamine. Alcohol can also make you feel sleepy and less alert. Taking them together can increase these effects, making you more drowsy, dizzy and less coordinated than usual. UK product information for Phenergan advises avoiding alcohol during treatment because it can increase the sedative effects of the medicine.
This guide explains what can happen when promethazine and alcohol are combined, how long the effects of promethazine may last, who may need to take extra care, and what to do if you have already had a drink after taking promethazine.
Key Side Effects and Things to Know
- Promethazine and alcohol can both cause drowsiness, and taking them together can increase sleepiness, dizziness and problems with coordination
- There is no official minimum waiting time between taking promethazine and drinking alcohol, so the product information advises avoiding alcohol while you are taking Phenergan
- Promethazine can have effects lasting for up to 12 hours, so drowsiness may continue into the following morning
- Older adults and people taking other medicines that cause drowsiness may be more affected
- Do not drive or operate machinery if you feel sleepy, dizzy, less alert or have blurred vision
How Promethazine and Alcohol Interact in the Central Nervous System
Promethazine is an antihistamine that blocks H1 histamine receptors and can cause sedation. It is also used for conditions such as allergies, nausea and vomiting, and short term insomnia in adults.
Alcohol affects the brain in a different way, but it can also make you less alert and more sleepy. When alcohol is taken with promethazine, the sedating effects can add together. This can make you feel more tired, dizzy or unsteady than you would after taking either one alone.
The effect can vary from person to person. Factors such as the amount of alcohol, the promethazine dose, other medicines and your general health can all make a difference.
How Does Promethazine Work When Mixed with Alcohol?
The main concern is increased sedation. You may feel unusually sleepy, dizzy or unsteady, and your ability to concentrate and react quickly may be affected.
This matters particularly for activities that need full attention, such as driving, cycling, using machinery or caring for another person. If you have taken promethazine and alcohol together, do not drive or operate machinery if you feel drowsy, dizzy or less alert.
Taking a large amount of alcohol, a higher than recommended dose of promethazine, or other medicines that cause drowsiness can increase the level of sedation. Other sedating medicines include sleeping tablets, some antidepressants, opioid painkillers and medicines used for anxiety.
For this reason, the UK product information advises avoiding alcohol while taking Phenergan rather than trying to work out how much alcohol might be acceptable.
Phenergan 25mg and Alcohol: Does the Strength Matter?
The interaction is possible with different forms and strengths of promethazine because it is linked to the medicine's sedating effect. Phenergan is available as 25mg tablets and as an oral solution.
A higher dose can cause more sedation, so taking 25mg may make you feel more sleepy than taking a lower dose. However, there is no recommended amount of alcohol that can be considered safe to combine with promethazine.
The same general advice applies whether you are taking branded Phenergan or another medicine containing promethazine hydrochloride: avoid alcohol while taking the medicine.
How Long After Taking Promethazine Can You Drink Alcohol?
There is no official minimum waiting time published for drinking alcohol after a dose of promethazine. Instead, the product information advises avoiding alcohol during treatment because it can increase the sedative effects of promethazine.
Promethazine can have a duration of action of up to 12 hours. This means a dose taken at bedtime may still have an effect the following morning, particularly if you still feel sleepy or dizzy.
If you are taking promethazine for short term insomnia, the medicine should not be used for more than seven days without medical advice. Avoiding alcohol during this short treatment period is simpler than trying to time a drink around when the medicine may have worn off.
Who Is at Greater Risk?
- Older adults, who may be more sensitive to the sedating and other effects of promethazine
- Anyone taking other medicines that cause drowsiness, including sleeping tablets, some antidepressants, opioid painkillers such as codeine or medicines used for anxiety
- Anyone with a condition that may be affected by promethazine, such as certain respiratory conditions, epilepsy, glaucoma, liver or kidney problems, or heart conditions
- Anyone taking medicines that can affect the heart rhythm, as promethazine can require extra caution with some of these medicines
- Anyone using promethazine for sleep who is considering alcohol as an additional way to become sleepy
If any of these apply to you, speak to a pharmacist or prescriber before taking promethazine with other medicines or if you are unsure about alcohol.
If You've Already Mixed Them
If you have already had alcohol after taking promethazine, do not take any more alcohol and do not drive or operate machinery. If you feel sleepy, dizzy or unsteady, stay somewhere safe and allow the effects to wear off.
Do not take an extra dose of promethazine to compensate for anything you have drunk, and do not take another medicine to try to counteract the drowsiness unless a healthcare professional has advised you to do so.
If you become very difficult to wake, have severe confusion, have serious breathing problems or become unresponsive, seek urgent medical help. Call 999 for severe breathing difficulty, unresponsiveness or another medical emergency.
If you are worried about the amount of alcohol or promethazine you have taken, or you are experiencing symptoms that concern you, contact NHS 111 or speak to a pharmacist for advice.
Using Promethazine for Sleep and Alcohol
Promethazine is licensed in the UK for short term insomnia in adults. It should not be used for more than seven days without medical advice.
Some people may consider having alcohol as well because they expect it to make them sleepier. This is not recommended. Alcohol can add to the sedating effect of promethazine and may leave you feeling more drowsy or less alert afterwards.
If you regularly need alcohol or another medicine to help you sleep, speak to a GP or pharmacist. There may be an underlying reason for your sleep problems that needs to be addressed.
Who Should Not Take Promethazine or Combine It with Other Medicines
Treatment suitability depends on your individual circumstances. The following points are general safety information and do not replace advice from a pharmacist, doctor or prescriber.
| Contraindication | Detail |
|---|---|
| Known hypersensitivity | Previous allergic reaction to promethazine or other phenothiazine medicines |
| Children under 6 years | Promethazine is contraindicated in this age group |
| Coma or CNS depression | Promethazine should not be used in people who are already experiencing central nervous system depression |
| MAOIs | Promethazine should not be taken with MAOIs or within the relevant period after stopping them |
| Use beyond 7 days | Short term insomnia treatment should not continue for more than seven days without medical advice |
Other conditions, including epilepsy, liver or kidney problems, Parkinson's disease, glaucoma, prostate enlargement and some heart conditions, may require extra caution. Certain medicines can also interact with promethazine, including some sedatives, sleeping medicines, antidepressants and medicines that can affect heart rhythm.
Speak to a pharmacist or prescriber before taking promethazine if any of these apply to you or if you regularly drink alcohol. Tell them about all medicines and supplements you take so they can check for possible interactions.
Phenergan Tablets and Elixir: Your Options
EverydayMeds supplies branded Phenergan in two formats. Both require a short online safety check before purchase. Phenergan tablets and elixir are Pharmacy (P) medicines in the UK, so a pharmacist can assess whether the medicine is suitable for you before supply.
| Product | Strength | Pack size | Price |
|---|---|---|---|
| Phenergan Tablets | 25mg promethazine hydrochloride | 56 tablets | £14.99 |
| Phenergan Elixir | 5mg in 5ml oral solution | 100ml | £14.49 |
The elixir is a liquid medicine. Follow the product instructions and use an appropriate measuring device so that you take the correct amount.
Prices shown are EverydayMeds' standard listed prices at the time of writing and can change. Check the product page for the latest price and pack information before ordering.
Medical Disclaimer
This article is provided for general information only and does not constitute medical advice. It is not a substitute for a consultation with a qualified healthcare professional.
Promethazine should be used according to the product instructions or advice from a pharmacist, doctor or prescriber. Tell your pharmacist, GP or prescriber about all medicines and supplements you are taking, particularly medicines that can cause drowsiness.
If you are unsure about combining promethazine with alcohol, speak to a pharmacist or another appropriately qualified healthcare professional before drinking.
If you develop concerning symptoms after taking promethazine, seek medical advice. In an emergency, call 999 or go to your nearest A&E.
