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Terms Of Use


Brand Name(s) : ALLERcalm, Allerief, Boots Allergy Relief, Hayleve, Piriton, Pollenase
Side Effects


Chlorphenamine should be used with caution by:

It should not be used by:

  • People who are allergic to chlorphenamine, or any of the ingredients in the medicine
  • People who are allergic to anti-histamines
  • People with severe liver disease
  • People taking monoamine oxidase inhibitors (MAOIs) or are within two weeks of stopping (used to treat mental health problems, e.g. phenelzine, isocarboxazid)
  • Children under one year of age (syrup)
  • Children under six years of age (tablets)
  • Neonates (injection)
  • People with rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption (for certain tablets only, please consult your doctor or pharmacist for more details)
  • People with rare hereditary problems of fructose intolerance (for use of syrup form only)

Also see list of precautions and interactions


Do not store above 25°C. Store in a dry place in the original carton to protect from light.


What is it used for?

  • Chlorphenamine is used to treat allergies.
  • It is a sedating antihistamine.
  • It is used to relieve symptoms of allergic reactions.
  • In general this drug is used to treat a variety of allergic conditions, and the symptoms that arise from them, such as hayfever and insect bites. Hayfever is a condition with inflammation of the nose arising from an allergy to pollen. This leads to cold-like symptoms, such as sneezing, itchiness and a blocked or runny nose. Urticaria is a skin condition, often known as hives or nettle rash. The symptoms of urticaria include a red, itchy rash. Chlorphenamine is also used to treat vasomotor rhinitis which has similar symptoms to hayfever and arises from oversensitive blood vessels in the nose. This medicine is given by injection when fast control of allergic symptoms is needed.
  • Benefits of being on this drug can include relief from the symptoms of the allergic reactions.

Listed below are the typical uses of chlorphenamine.

  • Hayfever
  • Vasomotor rhinitis
  • Urticaria
  • Angioneurotic oedema (swelling of the eyes, lips, tongue or throat)
  • Food allergy
  • Allergic drug and serum reactions
  • Allergic reactions to Insect bites and stings
  • Desensitisation reactions (hospital tests to lower your allergic response to an specific allergen, such as a specific pollen or food-injection only)
  • Severe pruritis (itch)
  • Itch associated with chickenpox

On occasion your doctor may prescribe this medicine to treat a condition not on the above list.


This medication can be taken in tablet form, syrup form or as an injection.

How often do I take it?

  • Tablet or syrup form: take this medication orally, usually every four to six hours, with or without food.

Injection form: this medication will be given to you by a doctor or nurse by either the intravenous (into a vein), intramuscular (into a muscle) or subcutaneous (beneath the skin) route.

Use this medication as required in order to get the most benefit from it.

Remember to use it at the same time each day - unless specifically told otherwise by your doctor.

It may take up to one to two hours before the full benefit of this drug takes effect.

Certain medical conditions may require different dosage instructions as directed by your doctor.

What dose?

  • Dosage is based on your age, gender, medical condition, response to therapy, and use of certain interacting medicines.

Do I need to avoid anything?

  • This medication may cause drowsiness, blurred vision and decreased awareness, which can seriously impair the ability to drive and operate machinery. Consult your doctor or pharmacist for more details. Alcohol intake should be avoided while taking this medication.

When can I stop?

  • Tablet or syrup form: use as required, and as directed. If symptoms do not go away within five days of use of medication then consult your doctor or pharmacist.

Injection form: Always complete the full course as prescribed by your doctor.


  • Sedative effects from drowsiness to deep sleep
  • Lack of concentration
  • Tiredness
  • Dizziness
  • Decreased awareness
  • Headache
  • Irritability
  • Difficulty passing urine
  • Dry mouth
  • Blurred vision
  • Problems with the gut including abdominal pain, indigestion, nausea, vomiting, diarrhoea
  • Loss of appetite (which may lead to anorexia)
  • Skin rashes, including urticaria (also known as hives, nettle rash), sensitivity to light
  • Yellowing of eyes and skin
  • Inflammation of the liver
  • Productive cough (phlegm on chest)
  • Chest pain
  • Increased or abnormal heart rate
  • Low blood pressure
  • Anaemia and other blood disorders
  • Muscle weakness and movement difficulties
  • Ringing in the ears
  • Depression
  • Hyperactivity in children
  • Confusion in elderly
  • For syrup only: If this medication is taken long term then there may be a increase in risk of tooth decay so dental hygiene is important.
  • For injection only: reactions at site of injection such as a burning or stinging sensation. The injection may result in a lowering of blood pressure (hypotensive effect).

If any of these persist or you consider them severe then inform doctor or pharmacist.

Tell your doctor immediately if you develop any of the following symptoms:

  • Yellowing of eyes and skin in newborn babies

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

A serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

The Yellow Card Scheme allows you to report suspected side effects from any type of medicine (which includes vaccines, herbals and over the counter medicines) that you are taking. It is run by the medicines safety watchdog called the Medicines and Healthcare products Regulatory agency (MHRA). Please report any suspected side effect on the Yellow Card Scheme website.


Before taking chlorphenamine, tell your doctor or pharmacist if you are allergic to it; or to other antihistamines; or if you have any other allergies.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have:

  • Allergy to chlorphenamine, or any of its ingredients
  • Allergy to anti-histamines
  • Severe liver disease
  • Rare hereditary problems of galactose intolerance, the Lapp lactase deficiency or glucose-galactose malabsorption (for certain tablets only, please consult your doctor or pharmacist for more details)
  • Rare hereditary problems of fructose intolerance (for use of syrup form only)

Before using this medication, tell your doctor or pharmacist your medical history, especially any of the following:

  • Epilepsy
  • Severe heart failure
  • Decreased liver function
  • Glaucoma (increased pressure in the eye)
  • Difficulty passing urine
  • Enlarged prostate gland (prostatic hypertrophy)
  • Obstructive disease of the stomach or intestine
  • Bronchietasis
  • Asthma or bronchitis
  • Overactive thyroid gland (hyperthyroidism)
  • Severe high blood pressure (hypertension)
  • Porphyria (rare blood disease)
  • Diabetes mellitus (for use of syrup form only)

The use of this medication should be stopped at least 48 hours before having a skin test, as chlorphenamine could make the results unreliable.

Before having surgery, tell your doctor or dentist that you are taking this medication.

Does alcohol intake affect this drug?

  • It is recommended not to drink alcohol while taking this medication, as the effects of alcohol may be increased.

The elderly: chlorphenamine should be used with caution in the elderly as they may be more likely to get some of the side effects associated with this medication.

Pregnancy and breastfeeding - please ensure you read the detailed information below


The safety of chlorphenamine has not been established during pregnancy, and is therefore not recommended. Ask your doctor or pharmacist if you have any doubts or questions about this.

It is sensible to limit use of medication during pregnancy whenever possible. However, your doctor may decide that the benefits outweigh the risks in individual circumstances and after a careful assessment of your specific health situation.

If you have any doubts or concerns you are advised to discuss the medicine with your doctor or pharmacist.


It is not known whether chlorphenamine passes into breast milk. The manufacturer therefore states that it should not be taken if you are breastfeeding.

It is sensible to limit use of medication during breastfeeding whenever possible. However, your doctor may decide that the benefits outweigh the risks in individual circumstances and after a careful assessment of your specific health situation.

If you have any doubts or concerns you are advised to discuss the medicine with your doctor or pharmacist.


Before using this medicine, tell your prescriber of all the medicines you are taking including prescription medicines and medicines you have bought over the counter without a prescription. Tell your prescriber if you are taking vitamins or complementary remedies such as herbal products, as these can also interact with medicines.

If you are taking more than one medicine, these may interact with each other. Your prescriber may decide to use medicines which interact with each other if the benefit outweighs the risks. In these cases, the dose of your medicines may need to be adjusted or you may be monitored more closely.

The following medicines may interact with chlorphenamine:

  • Monoamine oxidase inhibitors (MOAIs) or within two weeks of stopping (used to treat mental health problems, e.g. phenelzine, isocarboxazid)
  • Other antidepressants such as amitriptyline, imipramine
  • Hypnotics (sleeping tablets)
  • Medicines for anxiety
  • Other sedating antihistamines for allergies, such as hydroxyzine, promethazine
  • Medicines which have an anticholinergic effect such as some used to treat
  • Phenytoin used to treat epilepsy

This information does not contain all possible interactions. Therefore, tell your prescriber of all the products you are using before taking this medicine.

If you have a question or want to discuss anything about your medicine, speak to your local pharmacist.


Talk to your doctor to go to your nearest hospital straight away. Take the medicine and leaflet with you.

Signs of an overdose include drowsiness, fits, temporary pause in breathing, muscle spasms of the neck, shoulders and body, circulatory problems including collapse and irregular heart beat, dry mouth, fever, constipation, blurred or double vision and difficulty urinating, dilation of the pupil of the eye, glaucoma and blockage of the small intestine, mental or behavioural changes, excitement or agitation.

In infants and children, symptoms of overdose may include poor co-ordination, excitement, tremors, changes in behaviour, hallucinations and fits. Other symptoms may include dilated pupils, dry mouth and facial flushing.

If you think you, or someone you care for, might have accidentally taken more than the recommended dose of chlorphenamine or intentional overdose is suspected, contact your local hospital, GP or if in England call 111. In Scotland call NHS 24. In Wales, call NHS Direct Wales. In the case of medical emergencies, always dial 999.


If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

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Source: Selected from data included with permission and copyrighted by Boots UK Limited. This copyrighted material is sourced from a licensed data provider and is not for distribution, except as may be authorised by the applicable terms of use.
CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgement of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse events, nor should it be construed to indicate that use of a particular medicine is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any medicine, changing any diet, or discontinuing any course of treatment.

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