While you might not immediately recognize the name chlorphenamine, you’re likely familiar with brands like Piriton, Allerief, or Pollenase, which all feature this ingredient as their main active component. Chlorphenamine is generally safe for use by most adults and children over the age of 12 months. However, there are 12 specific groups who should use it with caution.

According to the NHS, individuals with certain health conditions should consult a doctor or pharmacist before using chlorphenamine. These precautions are important to ensure safe usage.

1. Anyone who’s had an allergic reaction to chlorphenamine or any other medicine
2. Anyone with an eye problem called primary angle closure glaucoma
3. Anyone who has taken a type of antidepressant called monoamine oxidase inhibitors in the last 14 days
4. Anyone with problems peeing or emptying their bladder
5. Anyone with epilepsy or another health problem that can cause fits or seizures
6. Anyone who has breathing difficulties such as asthma or a lung condition
7. Anyone who has heart disease or very high blood pressure
8. Anyone with an enlarged prostate
9. Anyone who has liver or kidney problems
10. Anyone due to have an allergy test, as taking chlorphenamine may affect the results, so you might need to stop taking it a few days before the test – ask a pharmacist or your doctor for advice
11. Anyone who is unable to have any alcohol – some liquid chlorphenamine products contain a very small amount of alcohol, so check the ingredients and the packaging carefully
12. Anyone who is a frail, older adult – they may have more side effects, such as confusion

The health service advises: “If you or your child has been prescribed chlorphenamine, it’s important to adhere to your doctor’s instructions regarding dosage and timing. If you’ve purchased it from a pharmacy, follow the directions on the package, or seek advice from your pharmacist. Should you or your child not see improvement in symptoms within a few days, it’s recommended to consult a doctor.”

When using chlorphenamine, it’s crucial to be cautious about combining it with other medications, as this can lead to adverse reactions. If you’re taking other medicines, consult with your GP or pharmacist for guidance.

Additionally, children under six should avoid taking cough or cold medications that contain chlorphenamine in combination with other ingredients. The NHS cautions: “This is not an exhaustive list of medicines that may interact with chlorphenamine. For a comprehensive list, refer to the leaflet included with your medication.”

• A type of antidepressant called a monoamine oxidase inhibitor, such as phenelzine
• Phenytoin (an anti-epilepsy medicine)
• Any medicines for anxiety or to help you sleep
• Any medicine that makes you drowsy, gives you a dry mouth, or makes it difficult for you to pee – taking chlorphenamine might make these side effects worse

Children under six years old should also not take cough or cold medicines containing chlorphenamine along with other ingredients. Nonetheless, NHS guidance warns: “These are not all the medicines that may cause problems if you take them with chlorphenamine. For a full list, see the leaflet inside your medicine packet.”

It continues: “It’s safe to take chlorphenamine with painkillers like paracetamol or ibuprofen that you buy from a pharmacy or shop. But if you take chlorphenamine with painkillers that contain codeine (such as co-codamol) or other prescription painkillers, you’re more likely to have side effects.”

Chlorphenamine typically begins working between 30 minutes and one hour after consumption, with users advised to allow at least four hours between doses. Common adverse effects include feeling sick, dizziness, headaches, drowsiness, impaired vision and poor concentration.

Anyone experiencing dizziness, sleepiness, or blurred vision should avoid riding a bike or driving a car until their symptoms resolve. Alcohol should also be avoided when taking chlorphenamine.

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