Flexofen - Interactions | Adverse Effects

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

Flexofen contains fexofenadine (antihistamine drug). It is used in patients older than 12 years to relieve the symptoms of chronic idiopathic urticaria.

When Flexofen cannot be used

Flexofen should not be used in the following conditions:

  • If you have kidney problems
  • If you have liver problems
  • If you have heart problems
  • In patients older than 65 years

Flexofen can sometimes make you feel drowsy and in those situations, you should avoid driving.

Application of Flexofen during pregnancy and lactation

This drug belongs to a group C which means that animal studies have shown that this drug can have adverse effects on the fetus. Studies in animals have shown that this drug can lead to reduction in body weight of newborns.

The patient information leaflet states that this medicine is not recommended for use during breastfeeding. Studies found, however, that infants receive only 0.45 % of the dose of the mother's dose and in such small concentrations that unwanted effects are not expected.1 Consult your pediatrician and he or she will assess the benefits and risks of applying this drug during breastfeeding.

How should you take Flexofen?

Flexofen is applied orally with plain water, before a meal, and the recommended dose is one tablet or 180 mg per day.

If you take more than your doctor recommended, the following symptoms may occur:

  • drowsiness
  • dizziness
  • dry mouth


Medium (moderate) Flexofen interactions with other drugs include:

  • ACE inhibitors, such as: quinapril. This drug binds Flexofen in the stomach and reduces its absorption and effectiveness.
  • Antacids, such as: aluminum hydroxide, magnesium hydroxide, magnesium trisilicate and calcium carbonate. These drugs slow the absorption of Flexofen in the stomach, and reduce its efficacy. If you need to simultaneously apply these medications be sure to make a gap of at least 3 hours between taking these drugs.

Drugs that increase the concentration of Flexofen in the blood and consequently increase the risk of side effects are:

  • Antiarrhythmic medications, such as: dronedarone
  • Tyrosine kinase inhibitors, such as: cabozanitinib (a drug used in the treatment of renal cell carcinoma).
  • Medications used to treat hepatitis, such as: daclatasvir
  • Glucosylceramide inhibitors, such as: eliglustat - a drug used for the treatment of type 1 of Gauscher disease
  • Emergency contraceptives, such as: ulipristil acetate
  • Eluxadolin, a drug used to relieve symptoms of IRB (irritable bowel syndrome)
  • Flibanserin, a drug that is used to treat decreased libido in postmenopausal women

This medication didn't show any major interactions with other drugs and food.

Minor interactions are not mentioned in this article because they generally have no clinical significance.

Flexofen adverse effects

Common side effects of Flexofen include:

  • Emesis
  • Feeling drowsy
  • Feeling dizzy

Uncommon adverse effects include:

  • Fatigue

Other adverse effects with unknown frequency include:

  • Redness of the face
  • Sleep agitation
  • Irregular heartbeat
  • Allergic reaction


  1. NCBI link 1

Information on this website are provided for educational purposes only and are not intended for medical advice, diagnosis or treatment.

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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