Phenergan: Your Questions Answered
Phenergan, a brand name for the medication promethazine, is a well-known name in many UK households. As a first-generation antihistamine, it has a wide range of uses, from treating allergies and travel sickness to acting as a short-term sleep aid. Its versatility also means it generates a lot of questions about its uses, effects, and safety.
At My Pharmacy, we believe in providing clear, reliable information to help you use medications safely and effectively. This article answers your most common questions about Phenergan, helping you understand how it works and whether it’s the right choice for you.
You can find both Phenergan Tablets and Phenergan Elixir available at My Pharmacy.
What are Phenergan tablets used for?
Phenergan (promethazine) is licensed for a variety of conditions. Its primary uses include:
- Allergies: Treating allergic conditions like hay fever, nettle rash (urticaria), and reactions to insect bites.
- Short-term Insomnia: As a short-term sleeping aid for adults, due to its strong sedative effects.
- Travel Sickness: Preventing and treating nausea and vomiting associated with motion sickness.
- Nausea and Vomiting: Treating nausea from other causes, such as in the morning or after surgery.
What do they prescribe Phenergan for?
Doctors prescribe Phenergan for all the uses listed above. Because of its potent sedative effects, it’s often prescribed for insomnia when other treatments haven’t worked, or for severe allergies where a sedating antihistamine is beneficial (for example, to stop itching at night).
Can I buy Phenergan over the counter in the UK?
Yes, Phenergan is available to buy over the counter in UK pharmacies, including online at My Pharmacy, following a consultation with a pharmacist. It is a ‘Pharmacy Medicine’ (P), which means it’s not on general sale and a pharmacist needs to ensure it’s appropriate and safe for you to use.
Is Phenergan a strong sleeping tablet?
Yes, Phenergan is considered a strong sedative and is effective as a short-term sleeping aid. Its primary ingredient, promethazine, is a first-generation antihistamine, which are well-known for causing significant drowsiness. This effect is why it’s used for insomnia, but also why caution is needed, especially regarding next-day grogginess.
How quickly does Phenergan work?
When taken orally, Phenergan typically starts to work within about 20 minutes for its sedative and anti-nausea effects. The full effects are usually felt within 1-2 hours.
How long will I sleep if I take Phenergan?
The sedative effects of Phenergan can last for up to 12 hours. This means if you take it for sleep, you can expect it to help you stay asleep for a full night (around 8 hours). However, the long duration of action also means you might feel drowsy, groggy, or “hungover” the next morning. It’s crucial not to drive or operate machinery until you know how it affects you.
Do you get good sleep with Phenergan?
Many people find that Phenergan helps them fall asleep and stay asleep, providing a deep sleep. However, the quality of sleep can be subjective. Because it forces sedation, it may not feel as “natural” or refreshing as unmedicated sleep for some. The main benefit is for those whose sleep is severely disrupted by conditions like itching, anxiety, or insomnia.
Does Phenergan sedate you?
Yes, sedation is one of the most prominent effects of Phenergan. It’s a key reason it’s used as a sleep aid and a major side effect to be aware of when using it for other purposes like allergies.
Is Phenergan good or bad for you?
Phenergan is neither inherently “good” nor “bad.” It is an effective medication for its licensed uses when taken correctly and for a short duration. It becomes problematic (“bad”) if it’s used long-term for sleep, misused, taken with interacting substances like alcohol, or used by individuals who have health conditions that make it unsafe for them.
What are the side effects of Phenergan?
The most common side effect is drowsiness. Other side effects can include:
- Dizziness, restlessness, or confusion (especially in the elderly).
- Dry mouth.
- Blurred vision.
- Headache.
- Nightmares.
- Difficulty concentrating.
What is the downside of Phenergan?
The main downsides are the potent sedative effects which can impact you the next day, and its potential for anticholinergic side effects (dry mouth, blurred vision, etc.). It’s also only suitable for short-term use for insomnia, as tolerance can develop, making it less effective over time.
Why is promethazine a high risk medication?
Promethazine is considered a higher-risk medication, particularly in certain populations like the elderly and very young, due to:
- Strong Sedative Effects: Increases the risk of accidents, falls, and respiratory depression (slowed breathing).
- Anticholinergic Effects: Can cause confusion, urinary retention, and worsen conditions like glaucoma.
- Potential for Abuse: Although less common than other sedatives, there is a potential for misuse.
- Contraindications: It cannot be used in children under 2 years old due to the risk of fatal respiratory depression.
Why does Phenergan have a black box warning?
The “black box warning” is a requirement from the FDA in the United States, not the UK’s MHRA. The US warning highlights the severe risk of respiratory depression (breathing problems) in children under two and the risk of severe tissue injury if administered incorrectly via injection. While the UK doesn’t use the same “black box” format, the same safety concerns are recognised and are detailed in the Patient Information Leaflet.
Does Phenergan mess with your heart?
Phenergan can, in rare cases, affect the heart. It can cause palpitations (a noticeable heartbeat) or an irregular heartbeat (arrhythmia). People with pre-existing heart conditions should speak to their doctor before taking Phenergan.
Who should avoid Phenergan?
You should avoid Phenergan or consult a doctor if you:
- Are allergic to promethazine or other phenothiazines.
- Have severe breathing difficulties or are in a coma.
- Are taking other medications that cause sedation, including certain antidepressants (MAOIs).
- Have a history of glaucoma or problems with your prostate.
- Are pregnant or breastfeeding, unless advised by a doctor.
- It must not be given to children under the age of two.
What should you not take with Phenergan?
Do not take Phenergan with:
- Monoamine Oxidase Inhibitors (MAOIs) for depression.
- Other sedating medications, including other sedating antihistamines, strong painkillers (opioids), benzodiazepines, or other sleeping tablets, as this can dangerously increase sedation.
- Alcohol.
Can I have alcohol with Phenergan?
No. You should not drink alcohol while taking Phenergan. Alcohol significantly increases the sedative effects of the medication, which can lead to extreme drowsiness, dizziness, and dangerously slowed breathing. The combination greatly increases the risk of accidents.
Can you take Phenergan with paracetamol?
Yes, it is generally safe to take paracetamol with Phenergan. There are no known direct interactions between the two medications.
Does Phenergan have codeine in it?
No. Phenergan (promethazine hydrochloride) does not contain codeine. This is a very common point of confusion.
Why is promethazine with codeine no longer available?
In the past, a combination product called “Phenergan with Codeine” was available as a cough syrup. It was discontinued and is no longer available in the UK due to growing concerns about the risks associated with codeine, particularly the potential for misuse, addiction, and respiratory depression, especially when combined with a sedative like promethazine.
Is Phenergan good for anxiety?
While not licensed for anxiety in the UK, Phenergan’s sedative and relaxing effects can help to temporarily reduce feelings of anxiety and restlessness for some people. It is sometimes prescribed “off-label” for this purpose, particularly for short-term situations.
Does Phenergan relax you?
Yes, due to its sedative effect on the central nervous system, Phenergan can help you feel more relaxed and less agitated.
Can Phenergan make you feel depressed?
While not a common side effect, mood changes, including feeling depressed or disoriented, have been reported by some users. If you experience any new or worsening symptoms of depression while taking Phenergan, you should stop taking it and speak to your doctor.
What antihistamine is good for itching?
Phenergan is very effective for itching (pruritus), especially at night, because its sedative effect helps you to sleep without scratching. Other sedating antihistamines like chlorphenamine (Piriton) are also effective. For daytime use, non-drowsy antihistamines like cetirizine or loratadine are often preferred.
Does promethazine cause weight gain?
Long-term use of some antihistamines, including promethazine, has been associated with weight gain. This may be due to an increase in appetite or changes in metabolism. For the short-term use that Phenergan is recommended for, significant weight gain is unlikely.
Can you take 75mg of Phenergan?
The standard adult dose of Phenergan varies by what it’s being used for. For sleep, the dose is typically 25mg or 50mg at night. Doses should not exceed the maximum stated in the patient information leaflet. Taking a dose as high as 75mg would increase the risk of severe side effects and should only ever be done on the explicit advice of a doctor.
Can you build a tolerance to Phenergan?
Yes. If used for sleep every night, your body can build a tolerance to the sedative effects of Phenergan, meaning it becomes less effective over time. This is why it is only recommended for short-term use (a few days at a time).
How many days in a row can I take Phenergan?
For insomnia, Phenergan should only be used for short periods, typically no more than a few days to a week. If you find you need a sleep aid for longer than this, you should consult your doctor to address the underlying cause of your sleeplessness.
Can you take Phenergan on an empty stomach?
Yes, Phenergan can be taken with or without food. Taking it with food may help if you experience any stomach upset.
Can you fail a drug test for Phenergan?
Phenergan (promethazine) can potentially show up on some urine drug screens, specifically some that test for tricyclic antidepressants (TCAs) or phenothiazines, leading to a “false positive.” If you are subject to drug testing, it is important to declare that you are taking promethazine beforehand.
How long does Phenergan stay in your system?
The half-life of promethazine is roughly 10-14 hours. This means it takes that long for the concentration of the drug in your body to reduce by half. It can typically be detected in the system for 2-4 days after the last dose, depending on factors like your metabolism, dosage, and frequency of use.
Why do doctors not like prescribing promethazine?
While doctors do prescribe promethazine, some may be hesitant, particularly for long-term use, due to concerns about next-day drowsiness, the risk of falls in the elderly, the potential for tolerance, and the availability of newer antihistamines with fewer side effects for allergies. They prefer to address the root cause of issues like chronic insomnia rather than just treat the symptom with a sedative.
Has Phenergan been taken off the market?
No, Phenergan has not been taken off the market. It is still available in the UK as a pharmacy-only medicine. The formulation containing codeine has been discontinued, which may be the source of this confusion.
What is Phenergan called now?
Phenergan is still the brand name. The generic, non-branded name of the active ingredient is promethazine hydrochloride. You can buy the medication under either its brand name or its generic name.
What to use instead of Phenergan?
The best alternative depends on the reason for use:
- For Sleep: Other over-the-counter options include antihistamines like diphenhydramine (Nytol). Herbal remedies like valerian may also be considered. For persistent insomnia, consult a doctor.
- For Allergies: Non-drowsy antihistamines like cetirizine, loratadine, or fexofenadine are preferred for daytime use.
- For Travel Sickness: Other options include hyoscine hydrobromide (Kwells).
Why can’t I sleep after taking Phenergan?
In a small number of people, Phenergan can cause a “paradoxical reaction,” leading to excitement, restlessness, or agitation instead of sedation. This is more common in children and the elderly. If this happens, you should stop taking the medication and consult your pharmacist or doctor.
Final Thoughts on Using Phenergan
Phenergan is clearly a versatile and effective medication, but its strength and sedative properties mean it must be used with care and respect. We hope this guide has answered your key questions and empowered you to make an informed decision about your health.
Before starting any new medication, including Phenergan, it’s essential to read the patient information leaflet and speak with a healthcare professional. Our pharmacists are available to ensure it is the right and safe choice for your specific needs.
Further Reading: Online Pharmacies: Your Questions Answered
