Promethazine Hydrochloride

Promethazine hydrochloride is a drug used to mainly treat the symptoms of allergies. However, it also has several other benefits in being able to effectively treat the effects of motion sickness, the common cold, and aid sleep for those with short-term insomnia. 

In this Pharmacy Prime guide, we will be detailing everything you need to know about promethazine hydrochloride. We will be answering commonly asked questions such as ‘what is promethazine hydrochloride’ and ‘what is promethazine hydrochloride for’, as well as looking at branded medications such as Phenergan, and more.


In this medication guide, we will be going into depth about the medication promethazine hydrochloride, also known by its brand name Phenergan. By reading this guide, you will find answers and advice on the following topics:

  • What is promethazine hydrochloride?
  • What is promethazine hydrochloride for?
  • What is Phenergan?
  • What is Phenergan used for?
  • Medications that include promethazine hydrochloride
  • How long can you take promethazine hydrochloride?
  • Is promethazine hydrochloride safe?
  • How to take promethazine hydrochloride?
  • Potential side effects
  • Contraindications
  • Buy promethazine hydrochloride at Pharmacy Prime

What is promethazine hydrochloride?

Promethazine hydrochloride is an allergy medication primarily used to relieve allergy symptoms. It is an antihistamine, meaning that it blocks the effects of histamine within the body.

Histamine is a substance released when the body detects something that could harm it. However, this can be released when the body mistakes something non-harmful, such as dust or pollen. This leads to unpleasant symptoms such as watering eyes, a runny nose, and hives.

Such symptoms can be avoided by taking this promethazine hydrochloride before coming into contact with an allergen or reduced by taking it afterwards. Promethazine hydrochloride also has several other benefits in addition to its anti-allergy effects, which we will discuss below.

What is promethazine hydrochloride for?

Though promethazine hydrochloride is mainly used to treat allergy symptoms, it also has a range of benefits. As such, it is used to treat a wide variety of conditions, such as:

  • Allergy symptoms - As mentioned above, promethazine hydrochloride works as an antihistamine, helping to prevent or reduce the severity of an allergic reaction.
  • Motion sickness and vertigo - Promethazine hydrochloride can be used to prevent the brain’s responses to nausea and vomiting, making them useful in treating these symptoms caused as a result of vertigo and motion sickness.
  • Insomnia - The drowsy, sleep-inducing effect of promethazine hydrochloride makes it a useful aid for those with insomnia. However, it is not intended to be used as a permanent sleeping aid and is only recommended in treating cases of short-term insomnia. You should consult your doctor if you consistently have trouble sleeping and are looking to use this medication to treat it.
  • Cold symptoms - This medication can be particularly useful in treating cold symptoms, such as a runny nose or coughing. Some medications combine promethazine hydrochloride and paracetamol to help treat these symptoms more effectively.

What is Phenergan?

Phenergan is the branded name for promethazine hydrochloride. Both work in the same way, as they are the same medication just under a different name.

You can purchase Phenergan when choosing promethazine hydrochloride, though several other brands are available. You can also buy promethazine hydrochloride unbranded, which can often be cheaper than buying branded medication such as Phenergan.

What is Phenergan used for

Phenergan is used to treat the same conditions as promethazine hydrochloride mentioned above. It is effective in alleviating allergy symptoms, motion sickness, short-term insomnia, cold symptoms, and vertigo. Phenergan is simply one of many branded names for promethazine hydrochloride.

Medications that include promethazine hydrochloride

Promethazine hydrochloride is often sold individually in both branded and unbranded versions. However, this medication is also found as a component of other medications and under branded names other than Phenergan that you may recognise. Some of the more common medications you will see that contain promethazine hydrochloride include:

  • Night Nurse
  • Sominex
  • Avomine
  • Cold and flu medications

How to take promethazine hydrochloride?

Promethazine hydrochloride is taken orally. Before taking promethazine hydrochloride, ensure you familiarise yourself with the provided information leaflet. You should only take this medication as instructed by the information leaflet included in the box or under your doctor's or pharmacist’s advice.

The dose of promethazine hydrochloride you take will depend on several factors, such as your age and what you are using the medication for. Generally, lower doses are for using the medication to relieve allergy symptoms, whilst higher doses are used to treat short-term insomnia and travel sickness.

Promethazine hydrochloride should not be taken by certain individuals as it could be very likely to cause them harm. Explicitly, promethazine hydrochloride is contraindicated in children under the age of two. It is recommended against being taken by children between the ages of two and six but can be done so under a doctor’s advice.


For allergies (such as hay fever, rashes, and hives)


Children 6-10 years:

A single tablet (25mg) should be given at night. 25mg each day is the maximum dose for this age range.


Children over 10 years and adults (including the elderly):

Start with one tablet (25mg) taken at night. This can be increased to a maximum of one tablet (25mg) twice a day if needed.

For treatment and prevention of feeling sick or being sick (such as travel sickness)


Children 6-10 years:

10mg Tablets should be given in this age group


Children over 10 years and adults (including the elderly):

A single tablet (25 mg) should be taken the night before travelling. Another tablet may be taken after 6-8 hours if necessary.

As a short-term paediatric sedative and for short-term treatment of insomnia in adults


Children 6-10 years:

A single tablet (25mg) should be given at night.


Children over 10 years and adults (including the elderly):

One or two tablets (25-50mg) taken at night.

How long can you take promethazine hydrochloride?

Promethazine hydrochloride should not be taken for longer than seven days. You should first ask your GP or pharmacist if you intend to take this drug for longer than the recommended duration.

Is promethazine hydrochloride safe?

Promethazine hydrochloride is a safe, widely used medication that commonly poses no harm in short-term use. However, it should be noted that as with many medications, there is some risk of side effects, which we go into further detail about below.

Potential side effects

As with most medications, promethazine hydrochloride has several side effects that could occur as a result of its use. These include:

  • Nightmares
  • Restlessness
  • Hyperactivity
  • Headaches
  • Tiredness during daytime

If you are over the age of 65, you may experience:

  • Dry mouth
  • Difficulty weeing
  • Blurred vision
  • Feeling confused

This list of side effects is not exhaustive. As a result, you should refer to the package insert for further details and call 111 for a doctor’s advice if you experience these.


As mentioned above, those under the age of six should not take promethazine hydrochloride, but it is generally suitable for most adults. However, promethazine hydrochloride should not be taken if you:

  • Have bladder-related issues
  • Are trying for pregnancy
  • Have a history of seizures
  • Have narrow-angle glaucoma
  • Have an allergy to promethazine or similar medicines such as chlorpromazine and perphenazine

This list is not exhaustive. If you have any health conditions or are taking any medication which could potentially interfere with using promethazine hydrochloride, you should refer to a pharmacist’s or doctor’s advice before you do so.

Buy promethazine hydrochloride at Pharmacy Prime

If you are looking to use promethazine hydrochloride and know it is safe for you to do so, you can purchase Phenergan at Pharmacy Prime at competitive prices. You can purchase promethazine hydrochloride from our online store in the following forms:

Contact us

We hope this guide on promethazine hydrochloride has helped you to better understand the medication and help you assess if it’s suitable for you. If you would like to know more about the different medications we provide at Pharmacy Prime or have any other enquiries relating to our products, please get in touch with us. A member of our friendly team will be in touch to provide you with assistance.