Promethazine (Phenergan) is a long established option for preventing and easing travel sickness. However, taking it at the right time is important, and extra care is needed when considering its use in children. This guide explains what current UK guidance and product information say about using promethazine for travel sickness, including when to take it, how long its effects may last, and important age related considerations.
Key things to know
- For a long journey, NHS guidance recommends taking promethazine the night before. For a short journey, it can be taken 1 to 2 hours before travelling.
- UK product information does not give a specific onset time. It states that the duration of action may be up to 12 hours.
- Promethazine is contraindicated in children under 6 years of age for this use. Always check suitability with a healthcare professional.
- Promethazine is licensed for motion sickness and other conditions, including short term sleep difficulty and allergic conditions. It is not licensed as a treatment for anxiety.
How Promethazine Helps with Motion Sickness
Promethazine is a first generation antihistamine with additional anticholinergic effects. It blocks histamine and may also affect signals involved in the balance system, which can contribute to motion sickness.
This is why promethazine can be used specifically for travel sickness. It is different from medicines that are simply used to treat nausea and vomiting for other reasons.
When to Take Promethazine Before Travelling
According to NHS guidance on how and when to take promethazine, the timing depends on the length of your journey.
For a long journey, NHS guidance recommends taking promethazine the night before travelling. For a short journey, it can be taken 1 to 2 hours before you travel.
If motion sickness has already started, NHS guidance advises adults to take 25mg as soon as possible, followed by another 25mg that evening. If symptoms are still a problem, 25mg can be taken on the following evening.
Always check the instructions for your specific product, as the recommended dose can vary depending on the person and the reason for treatment.
How Long Does It Take to Work, and How Long Does It Last?
UK product information does not give an exact time for when promethazine starts working. It does state that its duration of action may be up to 12 hours.
This means it is better not to assume that a particular dose will provide protection for a full day. If you have a long journey, follow the timing instructions provided by the NHS, your prescriber, pharmacist, or the product information for your medicine.
A Note on Adjusting Dose by Type of Travel
You may come across advice suggesting that sea travel requires a higher dose than travelling by air or road because the motion can be different. However, current NHS guidance and UK product information do not recommend changing the dose based on your method of transport.
Do not take more promethazine simply because you are travelling by sea or expect a longer or more difficult journey. If your usual treatment does not seem suitable for a particular trip, speak with a pharmacist or prescriber before travelling.
Promethazine and Children
Promethazine is contraindicated in children under 6 years of age for travel sickness. If you are travelling with a child under 6, speak with a pharmacist or GP about suitable alternatives rather than giving them promethazine.
For children aged 6 to 9, the appropriate dose depends on the specific product and the child's circumstances. NHS guidance recommends checking with a doctor or pharmacist or following the instructions on the medicine's packaging.
We have not included a general dose for this age group because different products can have different instructions, and the appropriate dose may depend on factors such as age and, for some products, body weight.
From age 10, dosing may generally follow the adult pattern for some products, but you should still follow the instructions for the specific medicine you are using.
If a child may need travel sickness treatment, it is a good idea to check the appropriate option and dose with a pharmacist before the day of travel.
Is Promethazine Suitable for Flight Anxiety?
Promethazine is licensed for motion sickness and is also used for conditions such as allergies and short term sleep difficulty. It is not licensed as a treatment for anxiety, including anxiety specifically related to flying.
Promethazine can cause drowsiness, which may make some people feel more relaxed or sleepy, but this does not make it an anxiety treatment. It can also be used for sedation in some medical settings, but this is different from treating anxiety.
If you are worried about flying, speak with a GP about appropriate ways to manage flight anxiety. They can discuss suitable options, which may include psychological approaches such as graduated exposure.
For more information about who should and should not take promethazine, including cautions relating to seizure disorders, asthma, and other conditions, see our promethazine safety guide.
Tablets vs Elixir for Travel
Both tablets and elixir contain the active ingredient promethazine, but they are different formulations and may have different strengths and instructions.
Promethazine tablets are available in 10mg, 20mg, and 25mg strengths. The appropriate strength and dose depend on the person's age and the reason for treatment, so always follow the product instructions or advice from a healthcare professional.
Tablets may be convenient for adults who are comfortable swallowing them. An elixir may be useful for people who have difficulty swallowing tablets and may allow smaller doses to be measured where appropriate, including for some children aged 6 and over.
If you are unsure which formulation or dose is suitable, ask a pharmacist rather than estimating the dose yourself.
If Symptoms Start Mid Journey
If you did not take promethazine before travelling and motion sickness symptoms have already started, the approach can be different from preventative treatment.
For adults, NHS guidance recommends 25mg as soon as possible after symptoms begin, followed by another 25mg that evening. If symptoms continue, 25mg may be taken on the following evening.
Promethazine can also be used for nausea and vomiting in other circumstances, but the dose and treatment schedule can be different depending on the condition. Always follow the advice given by your healthcare professional or the instructions for your specific product.
Knowing whether you are taking promethazine to prevent travel sickness or to manage symptoms that have already started can help you follow the correct dosing instructions.
Practical Precautions While Travelling
- Do not drive or operate machinery after taking promethazine. It can cause drowsiness and may affect your coordination, concentration, and reaction times.
- Avoid alcohol while taking promethazine. Alcohol can increase drowsiness and may make other side effects more noticeable.
- If promethazine upsets your stomach, taking it with food, water, or milk may help. Follow the instructions for your specific product.
- Avoid taking promethazine with another medicine that can cause drowsiness unless a healthcare professional has advised you to do so.
- Do not take more than the recommended dose if your symptoms continue. Speak with a pharmacist or prescriber instead of increasing the dose yourself.
- If you miss a dose, follow the instructions in your product information leaflet. Do not take a double dose to make up for a missed one.
- If you need promethazine for an extended period, speak with a pharmacist, prescriber, or GP about whether continued use is appropriate.
Planning ahead can make travelling with promethazine easier, particularly because it can cause drowsiness. Common side effects include drowsiness, dry mouth, and dizziness. Check your dose and plan when you will take it before you travel, rather than trying to work it out at the airport or dockside. This can help you use the medicine safely and as directed.
Ready to order, or want to check if promethazine is right for you? Start your consultation or speak with our clinical team if you have questions about whether promethazine is suitable for you.
Available Treatments and Side Effects
| Treatment | Price |
|---|---|
| Phenergan 25mg (Promethazine Hydrochloride) - 56 Tablets | £14.99 |
| Phenergan Elixir 5mg/5ml Oral Solution - 100ml | £14.49 |
Prices update live and may change.
Medical Disclaimer
This page provides general information about using promethazine for travel sickness. It is not a substitute for personalised medical advice, diagnosis, or treatment.
Promethazine is contraindicated in children under 6 years of age. For children aged 6 to 9, the appropriate dose should be confirmed with a doctor or pharmacist and checked against the instructions for the specific product.
If you are unsure whether promethazine is suitable for you or your child, speak with your prescriber, pharmacist, or GP before using it.
