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Allegra-D 12 Hour Side Effects

Generic name: fexofenadine / pseudoephedrine

Medically reviewed by Last updated on May 4, 2021.

Note: This document contains side effect information about fexofenadine / pseudoephedrine. Some of the dosage forms listed on this page may not apply to the brand name Allegra-D 12 Hour.

For the Consumer

Applies to fexofenadine / pseudoephedrine: oral tablet extended release, oral tablet extended release 24 hr

Side effects requiring immediate medical attention

Along with its needed effects, fexofenadine/pseudoephedrine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur while taking fexofenadine / pseudoephedrine:

More common

  • Trouble in sleeping

Less common

Incidence not known

  • Difficult or labored breathing
  • difficulty swallowing
  • dizziness
  • fast heartbeat
  • feeling of warmth
  • fever
  • hives or welts
  • itching skin
  • itching, puffiness or swelling of the eyelids or around the eyes, face, lips or tongue
  • large, hive-like swelling on face, eyelids, lips, tongue, throat, hands, legs, feet, sex organs
  • reddening of the skin, especially around ears
  • redness of the face, neck, arms and occasionally, upper chest
  • shortness of breath
  • skin rash
  • tightness in chest
  • swelling of eyes, face, or inside of nose
  • unusual tiredness or weakness
  • wheezing

Side effects not requiring immediate medical attention

Some side effects of fexofenadine / pseudoephedrine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Less common

Incidence not known

  • Terrifying dreams causing sleep disturbances

For Healthcare Professionals

Applies to fexofenadine / pseudoephedrine: oral tablet extended release

Nervous system

Common (1% to 10%): Headache, drowsiness, dizziness

Frequency not reported: Nervousness, insomnia, sleep disorders[Ref]


Rare (less than 0.1%): Hypersensitivity reactions (e.g. angioedema, chest tightness, dyspnea, flushing, systemic anaphylaxis)[Ref]


Common (1% to 10%): Nausea[Ref]


Common (1% to 10%): Fatigue[Ref]


Rare (less than 0.1%): Rash, urticaria, pruritus[Ref]


Frequency not reported: Paranoia[Ref]

More about Allegra-D 12 Hour (fexofenadine / pseudoephedrine)

Consumer resources

Professional resources

Other Formulations

Related treatment guides


1. Cerner Multum, Inc. "Australian Product Information." O 0

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.