Fexofenadine hydrochloride (Allegra) is an antihistamine drug used in the treatment of hay fever and similar allergy symptoms. It was developed as a successor of an alternative to terfenadine. Fexofenadine, like other second and third-generation antihistamines, does not readily pass through the blood-brain barrier, and so causes less drowsiness than first-generation histamine-receptor antagonists.


Generic Name:                   Fexofenadine HCl

Therapeutic Category:    Respiratory Agent

Pharmacological Class:   Antihistamine

Composition:                      Welfex 120

Each film coated tablet contains Fexofenadine HCl USP 120 mg

Welfex 180

Each film coated tablet contains Fexofenadine HCl USP 180             mg

Welfex Suspension

Each 5 ml contains Fexofenadine HCl USP 30 mg

Pregnancy Category:       C

Presentation:                      Welfex Tablets

Available in the pack size as 10 tablets X 10 blisters

Welfex Suspension

Available in 60 ml bottle with a measuring cap

Mechanism of Action

Fexofenadine selectively blocks the H1- receptors. This blockage prevents the activation of the H1 receptors by histamine. Prevents the symptoms associated with allergies brought by histamine. Fexofenadine exhibits no anticholinergic, antidopaminergic, alpha1-adrenergic or beta-adrenergic-receptor blocking effects.


  • Seasonal allergic rhinitis 
  • Chronic idiopathic urticaria


Route of administration: Oral

Adults and Children 12 Years and Older 120 and 180 mg Welfex tablet once daily.

Children 2 to 11 Years:  30 mg (5ml) Welfex Suspension twice daily.

Pediatric 6 months to less than 2 years: 15 mg (2.5 mL) Welfex Suspension twice daily.

Better efficacy if taken in empty stomach.


Absorption: Bioavailability 33%

Protein binding: Approximately 60-70%

Metabolism: Hepatic

Route of elimination: Feces (80%) and Urine (10%)

Half-life: 14.4  hours

Adverse Effects

Most common side effect demonstrated in adults are:

  • Headache
  • Some also experienced back and muscle pain, miosis* or pinpoint pupils*, nausea, drowsiness, and menstrual cramps.
  • Rare effects are anxiety and insomnia.

The most common side effects in children aged 6-11 years: 

  • Cough, upper respiratory tract infection, fever, and otitis media

        For children aged 6 months to 5 years:

  • Fatigue 


WELFEX is contraindicated in the following populations and situations:

  • Hypersensitivity to histamine or any component of the formulation


  • People with Bronchial asthma and peptic ulcer disease


  • Antacids containing aluminum or magnesium should not be taken within 15 minutes of fexofenadine as they reduce the absorption of fexofenadine by almost 50%
  • Taking erythromycin or ketoconazole while taking fexofenadine does increase the plasma levels of fexofenadine, but this increase does not influence the QT interval.
  • Fexofenadine is not to be taken with apple, orange, or grapefruit juice because it could decrease absorption of the drug and should therefore be taken with water


Miosis: Excessive constriction of the pupil of the eye

Pinpoint pupils: Pupils that are abnormally small under normal lighting conditions