Antihistamines

Antihistamines are used to relieve itch, redness and swelling in some skin conditions and other types of allergy. They also help to relieve some of the symptoms of the common flu and hay fever, like sneezing, runny nose and watery eyes.

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What is this medication used for?

Antihistamines are used to relieve itch, redness and swelling in some skin conditions and other types of allergy. They also help to relieve some of the symptoms of the common flu and hay fever, like sneezing, runny nose and watery eyes.

They work by cancelling the effects of histamine produced by the body in allergic conditions.

Drowsy

Non-drowsy

  • Buclizine

  • Chlorpheniramine

  • Hydroxyzine

  • Promethazine

  • Bilastine

  • Cetirizine (may cause mild sedation)

  • Desloratadine

  • Fexofenadine

  • Levocetirizine

  • Loratadine

  • Rupatadine

Related: When Allergies Occur

Dosage and How to Use

Antihistamines are available in tablets or liquids. Follow the dosage instructions on the label. Do not take more than recommended unless advised by your doctor.

Take this medicine with some food to reduce stomach irritation if necessary.

​For patients taking Bilastine:

  • Take Bilastine one hour before or 2 hours after intake of food or fruit juice.​

Missed a Dose

Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose.

Do not take double the dose to make up for the missed one.

Related: Know Your Medication

Side Effects, Precautions, Contraindication

What other effects may antihistamines cause?

Certain side effects of this medicine are not unusual and may even disappear during treatment. If any of the following effects persist or are severe, consult your doctor:

  • Some antihistamines may cause some people to feel drowsy, while other antihistamines do not have this effect at all. If you are affected, do not drive, operate machinery or do work that requires you to be alert.

  • Blurred vision

  • Difficult or painful urination

  • Dry mouth (drink fluids or suck sweets to relieve this)

  • GI upset (bloating, constipation or diarrhoea)

What precautions should you take?

  • For women: Tell your doctor if you are pregnant, plan to become pregnant or are breast-feeding.

  • Inform your doctor if you regularly use other medicines that make you sleepy (such as cold or allergy medicine, sedatives, narcotic pain medicine, sleeping pills, muscle relaxants, and medicine for seizures, depression, or anxiety). They can add to sleepiness caused by antihistamines.

  • Avoid drinking alcohol. Alcohol may increase drowsiness or dizziness while taking antihistamines.

  • Inform your doctor that you are taking antihistamines before you have any skin tests for allergies. The results of the test may be affected by antihistamines.

  • Inform your doctor if you are taking over-the-counter medicines, including vitamins, minerals, and herbal products.

Related: Drug Allergy

Handling and Storage

  • Keep this medicine away from heat and direct sunlight in a cool, dry place, out of reach of children.

  • Do not keep this medicine with other medications in the same container. Keep medicines separately in labeled containers.

When in doubt, consult your doctor or pharmacist

National Skin Centre
1 Mandalay Road, Singapore 308205
Tel: 63508454​

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