Flonidan - Precautions | Use | Overdose

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

Flonidan is a drug that is manufactured by pharmaceutical company Novartis and contains the active ingredient loratadine - a non-sedating antihistamine. By blocking histamine H1 receptors, it inhibits the binding of histamine (the primary mediator of allergic reactions) on the histamine receptors, which hinders histamine's effects. So, Flonidan acts by relieving the symptoms of an allergic reaction.

Its chemical structure is similar to some antidepressants, but this medication does not pass the blood-brain barrier, and does not exhibit antidepressant or sedative properties. It binds mostly to the peripheral receptors and does not affect central nervous system functions.

It is very effective in relieving symptoms in the following situations:

  • Hay fever (allergic rhinitis), to relieve symptoms such as:
    • runny nose
    • sneezing
    • nasal congestion
    • burning eyes
    • itching eyes
  • Urticaria
  • Allergic reaction to mosquito bites (it is also effective in children older than 2 years). In one study performed in 28 children older than 2 years, it was proved that this medication significantly reduces itching and skin lesions caused by the mosquito bites.1
  • Allergic bronchial asthma. Although the PIL did not state that this medication can be used in alleviating the symptoms of allergic asthma, there are studies that show that the active substance of this drug - loratadine, effectively relieves the symptoms of allergic asthma and improves pulmonary function.2

When do you need to take precautions?

Flonidan is metabolized in the liver via the CYP3A4 and CYP2D6 enzyme, and patients with severe hepatic impairment should not apply this medicine. In these patients, the liver cannot metabolize the drug, which means that it will be very slowly eliminated from the body, which can lead to unwanted effects of this medicine.

Cases of severe liver damage due to the application of this medication have been reported.3

Given that approximately 40% of this medicine is eliminated through the urine, exercise caution when applying this medicine in patients with severe renal impairment.

Flonidan - use during pregnancy

The active substance of Flonidan - loratadine is classified into group B according to the FDA. Flonidan (loratadine) was not teratogenic in animal studies, but the safety of its use during pregnancy in humans has not been proven. Some studies in Denmark have shown that exposure to loratadine during pregnancy is a possible factor for occurrence of hypospadias (abnormal urination in boys) in newborns.4 Consult your doctor if you are pregnant and you have an allergic response.

Flonidan - use during breastfeeding

Studies have shown that infants receive about 0.46% of the dose that the mother took through breast milk.5 This is a small amount of the medicine and should not cause adverse effects in infants, but still exercise caution when applying this medication during breastfeeding. Consult your physician if you have an allergic reaction when you should breastfeed your baby. There have been reports that the use of this medicine during breastfeeding causes unusual irritability in infants.

The impact on the awareness and operating machinery

Very rarely, this medicine can cause sedation and in these situations, patients should not operate machinery.

How to apply Flonidan

The dosage is made according to the body weight.

Adults and children older than 2 years who have a body weight greater than 30 kg should take one tablet of Flonidan (10 mg) daily. This medication starts working in just one hour and the effects last for 10 - 24 hours (half-life is approximately 8.5 hours).

In children whose body weight is less than 30 kg, it is recommended to use Flonidan oral suspension 1 mg / 1 ml.

It should not be used in children younger than 2 years, because of the increased risk of unwanted anticholinergic effects.6


Symptoms of Flonidan overdose are:

  • Drowsiness
  • Rapid heartbeat
  • Palpitations

Interactions with medicines and food

Flonidan doesn't usually enhance the effects of alcohol, but a combination with alcoholic beverages should be avoided.

There are no interactions of this medicine with other drugs that have major clinical importance, but there are a many possible interactions of moderate clinical importance with all drugs that are inhibitors of CYP3A4 and CYP2D6 enzymes, such as:

  • Erythromycin
  • Clarithromycin
  • Ketoconazole
  • Cimetidine

These drugs cause a slight increase of Flonidan concentration in the blood, but it usually has no clinical significance.

Taking with food decrease the absorption of the active substance, but it has no significant impact on the effectiveness of this medicine.

Flonidan side effects

To reduce the occurrence of unwanted anticholinergic effects, it is recommended to drink plenty of water while you are on treatment with this medication.

This drug belongs to a newer generation of antihistamines, which exerts a significantly less number of side effects. Unlike other anti-allergic drugs, Flonidan doesn't inhibit noradrenaline reuptake and does not affect cardiovascular functions, and therefore does not cause cardiovascular side effects. Very rarely it can cause rapid heartbeat (tachycardia) or pounding heart feeling (palpitations). It does not prolong QT interval and does not cause arrhythmia.

Sedation, hyperexcitability and headaches are more common in the elderly.

The most common side effects of this drug (affects more than 2% of patients) are:

  • Headache
  • Drowsiness

Side effects that occur rarely (in less than 2% of patients) are:

  • Impotence and decreased libido
  • Disrupted salivation
  • Disturbance of taste
  • Impaired concentration
  • Dermatitis
  • Sinusitis
  • Pain in the ear and eye
  • Back pain
  • Leg cramps


  1. NCBI link 1
  2. NCBI link 2
  3. NCBI link 3
  4. NCBI link 4
  5. NCBI link 5
  6. Toxnet

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