Allegra-D 12 Hour Side Effects

Generic Name: fexofenadine / pseudoephedrine

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

Not all side effects for Allegra-D 12 Hour may be reported. You should always consult a doctor or healthcare professional for medical advice. Side effects can be reported to the FDA here.

For the Consumer

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

In addition to its needed effects, some unwanted effects may be caused by fexofenadine / pseudoephedrine. In the event that any of these side effects do occur, they may require medical attention.

If any of the following side effects occur while taking fexofenadine / pseudoephedrine, check with your doctor or nurse as soon as possible:

More common
  • Trouble in sleeping
Less common
  • Cough
  • dizziness
  • irregular heartbeat
  • nervousness
  • sore throat
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

Some of the side effects that can occur with fexofenadine / pseudoephedrine may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:

More common
  • Headache
  • nausea
Less common
  • Abdominal or stomach pain
  • agitation
  • anxiety
  • back pain
  • dry mouth
  • heartburn
Incidence not known
  • Terrifying dreams causing sleep disturbances

For Healthcare Professionals

Applies to fexofenadine / pseudoephedrine: oral tablet extended release


Gastrointestinal side effects have included nausea (7.4%), dry mouth (2.8%), dyspepsia (2.8%), throat irritation (2.3%), and abdominal pain (1.4%).


Cardiovascular side effects have included palpitations (1.9%).

Pseudoephedrine causes vasoconstriction which generally does not produce hypertension, but may be problematic for patients with preexisting hypertension. Arrhythmias may be produced in predisposed patients. Rarely, pseudoephedrine has been reported to cause coronary artery spasm and chest pain.

One report evaluated the effect with 60 mg of pseudoephedrine on individuals in a hyperbaric chamber at 1 atmosphere (simulated scuba dive to 66 feet of sea water). Pseudoephedrine and depth (simulated) were found to have significant but opposite effects on heart rate, although these effects were unlikely to be clinically significant during diving.

Nervous system

Nervous system side effects have included headache (13%), insomnia (12.6%), dizziness (1.9%), agitation (1.9%), nervousness (1.4%), and anxiety (1.4%).


In rare cases, rash urticaria, pruritus, angioedema, chest tightness, dyspnea, flushing and systemic anaphylaxis have been reported.

Hypersensitivity reactions have included fixed drug eruptions.


Respiratory side effects have included upper respiratory infections (1.4%).


Musculoskeletal side effects have included back pain (1.9%).

Disclaimer: Every effort has been made to ensure that the information provided is accurate, up-to-date and complete, but no guarantee is made to that effect. In addition, the drug information contained herein may be time sensitive and should not be utilized as a reference resource beyond the date hereof. This material does not endorse drugs, diagnose patients, or recommend therapy. This information is a reference resource designed as supplement to, and not a substitute for, the expertise, skill , knowledge, and judgement of healthcare practitioners in patient care. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate safety, effectiveness, or appropriateness for any given patient. does not assume any responsibility for any aspect of healthcare administered with the aid of materials provided. The information contained herein is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. If you have questions about the substances you are taking, check with your doctor, nurse, or pharmacist.