A sedating antihistamine for allergies
Dexchlorpheniramine
A sedating antihistamine used to relieve allergy symptoms such as hay fever, itching and rashes.
What is Dexchlorpheniramine?
Dexchlorpheniramine is a sedating antihistamine used to relieve allergy symptoms such as hay fever (allergic rhinitis), itching, hives and allergic skin reactions. It works by blocking histamine, the chemical that causes allergy symptoms. Because it is a sedating type of antihistamine, the most common effect is drowsiness, so it can affect driving and is best used with care. It can also cause antimuscarinic effects such as a dry mouth, blurred vision and difficulty passing urine, so it is used cautiously in some people.
Education and reference only. This is a plain-language guide to Dexchlorpheniramine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Dexchlorpheniramine is an antihistamine, a medicine used to relieve allergy symptoms. It is one of the older, 'sedating' antihistamines (closely related to chlorphenamine), which means it is more likely to cause drowsiness than the newer non-drowsy types. It is used for allergic conditions such as hay fever and other allergic rhinitis, itchy skin, nettle rash (hives) and other allergic reactions. It is taken by mouth and works fairly quickly to ease symptoms.
How it works
When the body reacts to an allergy trigger, it releases a chemical called histamine, which causes the sneezing, itching, runny nose and rashes of an allergic reaction. Dexchlorpheniramine blocks the action of histamine, so these symptoms settle. Because it is an older antihistamine that passes into the brain, it also tends to cause drowsiness, and it can have 'antimuscarinic' effects such as a dry mouth and blurred vision. The newer, non-drowsy antihistamines block histamine without entering the brain as much, which is why they cause less sleepiness.
Company & origin
Originated / developed by: Generic manufacturers.
A sedating antihistamine used to relieve allergy symptoms; closely related to chlorphenamine.
What it treats
Conditions Dexchlorpheniramine is used for
Practical use
How to take Dexchlorpheniramine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it by mouth as directed, and be aware it can make you drowsy.
- Do not drive or operate machinery if it makes you sleepy.
- Avoid alcohol while taking it, as this increases the drowsiness.
- Tell your pharmacist or prescriber if you have glaucoma, prostate problems or difficulty passing urine, as it may not be suitable.
- Ask your pharmacist about a non-drowsy antihistamine if daytime sleepiness is a problem.
Weighing it up
Advantages & disadvantages of Dexchlorpheniramine
Advantages
- Effectively relieves allergy symptoms such as hay fever, itching and hives.
- Works fairly quickly to ease symptoms.
- The drowsiness it causes can occasionally help with sleep when symptoms are troublesome at night.
Disadvantages
- Commonly causes drowsiness, which can affect driving and daily activities.
- Can cause antimuscarinic effects such as dry mouth, blurred vision and difficulty passing urine.
- Often less suitable than non-drowsy antihistamines for daytime use.
Practical use
Good to know
The main thing to understand about dexchlorpheniramine is that it is a sedating antihistamine, so drowsiness is common; this can be a drawback during the day but is sometimes useful at night when allergy symptoms or itching disturb sleep. Because of the drowsiness, it can affect your ability to drive or operate machinery, and alcohol makes the sleepiness worse. It can also cause antimuscarinic effects such as a dry mouth, blurred vision, constipation and difficulty passing urine, which is why it is used with caution in older people and in those with conditions such as glaucoma, an enlarged prostate or urinary problems. Many people now choose a non-drowsy antihistamine for daytime allergy symptoms; your pharmacist can advise which suits you best.
Who should not take it / use with caution
- People who have had a serious allergic reaction to dexchlorpheniramine or similar antihistamines should not take it.
- It is used with caution in older people, who are more sensitive to its drowsy and antimuscarinic effects.
- It is used with caution in people with glaucoma, an enlarged prostate, urinary problems or certain other conditions.
Monitoring
- Reviewing whether allergy symptoms are well controlled.
- Watching for excessive drowsiness, especially in older people.
- Watching for antimuscarinic effects such as difficulty passing urine.
Side effects
- Drowsiness or feeling sleepy.
- Dry mouth, blurred vision or constipation.
- Difficulty passing urine, particularly in older men.
- Less commonly, dizziness, headache, or in children sometimes the opposite of drowsiness, with restlessness.
Key interactions
- Alcohol and other medicines that cause drowsiness, such as sleeping tablets or strong painkillers, add to the sleepiness.
- Other medicines with antimuscarinic effects can add to dry mouth, constipation and urinary problems.
- Tell your pharmacist or prescriber about all your medicines before taking it.
Available as: Tablets and an oral liquid taken by mouth.
Answers
Dexchlorpheniramine: frequently asked questions
What is dexchlorpheniramine used for?
It is a sedating antihistamine used to relieve allergy symptoms such as hay fever and other allergic rhinitis, itchy skin, hives and allergic reactions.
Will it make me drowsy?
Yes, it is a sedating antihistamine, so drowsiness is common; do not drive or operate machinery if it affects you, and avoid alcohol.
How is it different from non-drowsy antihistamines?
Newer, non-drowsy antihistamines block histamine without entering the brain as much, so they cause less sleepiness; many people prefer them for daytime use.
Can older people take it?
It is used with caution in older people, who are more sensitive to drowsiness and to effects such as dry mouth and difficulty passing urine.
Can I drink alcohol with it?
It is best to avoid alcohol, as it increases the drowsiness this antihistamine can cause.
The wider class
About Sedating (first-generation) antihistamine
Dexchlorpheniramine belongs to the sedating (first-generation) antihistamine class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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