If you are looking up how much Phenergan to take for sleep, the answer depends on the product and your individual circumstances. For adults, the UK product information gives a usual night time dose of 25mg or 50mg for short term treatment of insomnia. Phenergan is not intended for long term sleep problems, and it must not be given to children under 6 years of age. This guide explains the adult dose, answers the common "50mg" question and looks at why using promethazine to make children sleep is not recommended.
The Standard Adult Dose for Sleep
For adults using Phenergan (promethazine) for short term difficulty sleeping, the UK product information gives a dose of 25mg or 50mg as a single dose at night. For the 25mg tablet, this means one or two tablets.
Do not increase the dose yourself if you feel that the medicine is not working well enough. The patient information leaflet says that if the effect feels too weak or too strong, you should speak to your doctor or pharmacist rather than changing the dose yourself.
There is no need to try to time the effect to the minute. Take it as directed when you are ready to settle for the night, and make sure you have enough time to sleep before you need to be fully alert again.
What About 50mg for Sleep?
The 50mg question is worth clearing up because there is some conflicting information online.
For Phenergan 25mg tablets, the UK product information states that adults can take 25mg or 50mg as a single night time dose for short term treatment of insomnia. There is no 50mg Phenergan tablet listed for the UK product, so a 50mg dose using the 25mg tablets would mean taking two tablets.
However, that does not mean you should increase your dose to 50mg yourself. If you have been advised to take 25mg and it is not helping, speak to a pharmacist or doctor before taking more.
Taking a higher dose can increase the risk of side effects such as drowsiness, dizziness, dry mouth and blurred vision. It may also leave you feeling less alert the following day.
Why Phenergan Is Not a Medicine to Make Young Children Sleep
This is an important point because searches for "Phenergan for children's sleep" can be misleading.
Phenergan must not be given to children under 6 years of age. UK product information also lists short term use as a paediatric sedative for children aged 6 years and above, but this is different from using the medicine routinely to treat a child's sleep problems. Promethazine can cause unwanted effects in children, including excitation and agitation.
If your child is having trouble sleeping, do not use Phenergan simply to make them sleepy. A regular bedtime routine and good sleep habits are usually a better starting point. If sleep problems continue, speak to your GP or health visitor about what may be causing them and what support is appropriate.
Phenergan Tablets or Elixir
Phenergan is available in the UK as 25mg tablets and as Phenergan Elixir 5mg/5ml oral solution. Both contain promethazine hydrochloride, but the formulations and dosing instructions are different.
The 25mg tablet provides a fixed 25mg dose. The elixir is a liquid option for people who may find tablets difficult to swallow.
If you use the elixir, measure the dose using the measure supplied with the medicine rather than a kitchen spoon. Follow the instructions for the specific product you have and do not change the dose yourself.
If you have an allergy or sensitivity to any of the ingredients, check the patient information leaflet or ask a pharmacist before using it. The excipients are not identical between the tablet and elixir.
How Long to Use It, and When to Stop
Phenergan is intended for short term use. The UK patient information leaflet says not to take Phenergan for longer than 7 days. If your symptoms do not improve or become worse after 7 days, speak to a doctor or pharmacist.
This is important if you find yourself taking it night after night. Ongoing sleep problems may need a different approach and may have an underlying cause that needs to be looked at.
If you are regularly struggling to sleep, speak to your GP rather than continuing to use Phenergan without advice. Simple habits such as keeping a regular sleep schedule, having a relaxing bedtime routine and limiting caffeine late in the day may also help.
How Long the Effect Lasts
Promethazine is a long acting antihistamine and can cause drowsiness. The effects can last for several hours, so some people may still feel sleepy or less alert the following morning.
Keep this in mind if you need to get up early, drive or use machinery. Do not drive or operate machinery if you feel drowsy, dizzy or otherwise less alert.
Who Should Not Take It, Side Effects, and Cautions
Do not take Phenergan if you are under 6 years of age or if you are allergic to promethazine, other phenothiazines or any of the ingredients in the product. You should also not take it if you are taking an MAOI antidepressant or have stopped taking one within the previous 14 days.
Speak to a pharmacist or doctor before taking Phenergan if you have breathing problems such as asthma, epilepsy, glaucoma, an enlarged prostate, liver or kidney problems, heart problems or certain other health conditions. You should also check before taking it if you use other medicines, particularly medicines that can make you sleepy or have anticholinergic effects.
Phenergan can cause drowsiness, dizziness, blurred vision and other side effects that may affect your alertness. Avoid alcohol while taking it because alcohol can increase the sedative effects. Combining it with other sedating medicines can also increase these effects.
Seek urgent medical attention if you develop signs of a serious allergic reaction, such as difficulty breathing or swelling of the face, lips, mouth or throat. If you develop unusual bruising, bleeding, fever or a sore throat, contact your doctor promptly because these can sometimes be signs of serious blood related side effects.
If you are pregnant or breastfeeding, speak to your doctor or pharmacist before using promethazine. The medicine can cross the placenta and can pass into breast milk, so your individual circumstances should be considered.
Store Phenergan as directed on the packaging. For 25mg tablets, this means below 30°C and in the original carton to protect them from light. For Phenergan Elixir, store it below 25°C and use it within 1 month of opening.
Do not put unused medicines in household waste or wastewater. Ask your pharmacist how to dispose of medicines you no longer need.
