Allerfin - Dosage | Interactions | Effects

This article was medically reviewed by M.Pharm, Marko Tanaskovic on August 12, 2018. To read more about an author, click here.

Allerfin is a drug that contains chlorphenamine (H2 antihistamine) as an active substance. Histamine is a substance which is released in the body as a part of the allergic response and its binding to H2 receptors leads to the occurrence of itching and bronchospasm. By blocking histamine's action, Allerfin relieves allergy symptoms. It is used to relieve the symptoms of allergic reactions, such as:

  • Itching
  • Irritation
  • Swelling

Your doctor may prescribe this medicine if you have an allergic reaction to food, pollen, insect bite and other types of allergic reactions including anaphylaxis.


Allerfin should be administered with caution in the following conditions:

  • In patients with glaucoma (elevated intraocular pressure). Allerfin can increase the pressure in the eye and worsen glaucoma.
  • In patients who have heart disease or high blood pressure.
  • In patients with liver or kidney diseases. Allerfin is excreted by these organs and their impaired function means slower elimination from the body. This can increase concentration of this drug in the blood which increases the risk of side effects.
  • In patients with epilepsy.
  • In patients with enlarged prostate.

Use of this drug is contraindicated in patients who are taking, or have recently taken (in the last two weeks) medicines used for the treatment of depression and Parkinson's disease, which are called inhibitors of monoamine oxidase (MAOIs), such as: moclobemide, isocarboxazid, phenelzine, and selegiline. Drugs which have a similar chemical structure as MAOi (e.g. an antibiotic called linezolid) should also not be used concurrently with Allerfin.

Since it can cause drowsiness, you should not drive or operate machinery until you are on treatment with this drug.

There are data that suggest that this drug may cause photosensitivity (increased sensitivity of the skin to sunlight). If you are going to be out in the sun for long periods, it is necessary to use a sunscreen with an appropriate SPF.

Allerfin, pregnancy and breastfeeding

There is insufficient data on Allerfin and pregnancy. In general, the H2 antihistamines belong to the group B (according to FDA) because animal studies have shown no teratogenic effects. However, consult your doctor before you start using it during pregnancy.

It is assumed that small concentrations are excreted into breast milk, which can lead to excessive sleepiness in infants. For this reason, you should avoid breastfeeding while taking this drug.

It should not be administered concurrently with alcoholic beverages, because alcohol increases the risk of this drug toxicity.

How to use

Allerfin exists in the form of tablets at a dose of 2 mg and 4 mg as well as in the form of a syrup.

Recommended dosage is given in the table below:

Age Recommended dosage
>12 years 4 mg four or six times a day
6 - 12 years 2 mg four or six times a day
2 - 6 years 1 mg four or six times a day
1 - 2 years 1 mg two times a day

Note: In children younger than 6 years old Allerfin should be used in the form of syrup.

Take a pill with or without food. However, taking with food improves tolerability of gastrointestinal adverse reactions.


Allerfin should not be administered concurrently with the following drugs:

  • Propoxyphene (a drug used to treat severe pain). Concomitant use increases the risk of side effects (difficulty concentrating and dizziness).
  • Potassium preparations. Allerfin may increase the effect of potassium in the digestive tract, and concomitant use with this mineral should be avoided.
  • Topiramate - a drug used for migraine prevention. Concomitant use increases the risk of heat stroke.
  • Zonisamide - a drug used to treat partial seizures in epileptics. Concomitant use increases the risk of heat stroke.

Adverse effects

Possible adverse effects of Allerfin include:

  • Urinary incontinence
  • Dry mouth
  • Increased intraocular pressure
  • Stomach upset
  • Unexplained bleeding or bruising
  • Drowsiness
  • Collapse
  • Liver injury
  • Ringing in the ears
  • Nightmares
  • Confusion
  • Irritability
  • Difficulty concentrating


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If you have any concerns or questions about your health, you should always consult with a physician or other health-care professional.

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