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Xyzal Allergy 24HR Side Effects

Generic name: levocetirizine

Medically reviewed by Last updated on Feb 4, 2023.

Note: This document contains side effect information about levocetirizine. Some dosage forms listed on this page may not apply to the brand name Xyzal Allergy 24HR.


More frequent side effects include: drowsiness, fatigue, and nasopharyngitis. Continue reading for a comprehensive list of adverse effects.

Applies to levocetirizine: oral solution, oral tablet.

Serious side effects of Xyzal Allergy 24HR

Along with its needed effects, levocetirizine (the active ingredient contained in Xyzal Allergy 24HR) 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 immediately if any of the following side effects occur while taking levocetirizine:

Less common

Incidence not known

  • Anxiety
  • attack, assault, or force
  • bloody, cloudy, or dark urine
  • blurred or loss of vision
  • burning feeling while urinating
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • chills
  • clay-colored stools
  • confusion
  • cough
  • decrease in the frequency of urination
  • decrease in urine volume
  • deep or fast breathing with dizziness
  • diarrhea
  • difficult or labored breathing
  • difficulty in passing urine (dribbling)
  • difficulty with swallowing or speaking
  • discouragement
  • disturbed color perception
  • dizziness, fainting, or lightheadedness when getting up suddenly from a lying or sitting position
  • double vision
  • drooling
  • dry mouth
  • fast, irregular, pounding, or racing heartbeat or pulse
  • feeling of constant movement of self or surroundings
  • feeling sad or empty
  • fixed position of the eye
  • general tiredness and weakness
  • halos around lights
  • headache
  • hives or welts, itching, skin rash
  • inability to move the eyes
  • increased blinking or spasms of the eyelid
  • irritability
  • joint or muscle pain
  • lack of appetite
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or genitals
  • light-colored stools
  • loss of balance control
  • loss of interest or pleasure
  • muscle trembling, twitching, jerking, or stiffness
  • nausea
  • nervousness
  • night blindness
  • numbness of the feet, hands, and around the mouth
  • overbright appearance of lights
  • painful urination
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • redness of the skin
  • restlessness
  • rhythmic movement of the muscles
  • seeing, hearing, or feeling things that are not there
  • seizures
  • sensation of spinning
  • shaking
  • shuffling walk
  • sticking out of the tongue
  • stomach pain
  • swelling of the face, feet, or lower legs
  • thoughts of killing oneself
  • tightness in the chest
  • tremor
  • trouble concentrating
  • trouble with sleeping
  • tunnel vision
  • twisting movements of the body
  • uncontrolled movements, especially of the face, mouth, tongue, neck, and back
  • uncontrolled twisting movements of the neck, trunk, arms, or legs
  • unpleasant breath odor
  • unusual facial expressions
  • unusual tiredness or weakness
  • upper right stomach pain
  • vomiting with or without blood
  • weight gain
  • yellow eyes and skin

Other side effects of Xyzal Allergy 24HR

Some side effects of levocetirizine 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

  • Body aches or pain
  • dryness of the throat
  • earache
  • hoarseness
  • redness or swelling in the ear
  • tender, swollen glands in the neck
  • voice changes

Less common

  • Change in or loss of taste
  • difficulty in moving
  • increased appetite
  • joint pain or swelling
  • muscle pain, cramp, or stiffness
  • nightmares

For Healthcare Professionals

Applies to levocetirizine: oral solution, oral tablet.


The most frequently reported side effects were: somnolence, nasopharyngitis, fatigue, dry mouth, and pharyngitis (in 12 years and older); pyrexia, somnolence, cough, and epistaxis (in patients 6 to 12 years); pyrexia, diarrhea, vomiting, and otitis media (in patients 1 to 5 years); diarrhea and constipation (in patients 6 to 11 months).[Ref]

Nervous system

Common (1% to 10%): Somnolence, dizziness, headache

Uncommon (0.1% to 1%): Paresthesia, syncope

Rare (0.01% to 0.1%): Convulsion, movement disorder

Very rare (less than 0.01%): Dysgeusia, tremor, dystonia, dyskinesia

Frequency not reported: Orofacial dyskinesia, myoclonus, extrapyramidal symptoms

Postmarketing reports: Febrile seizure[Ref]


Very rare (less than 0.01%): Accommodation disorder, vision blurred, oculogyration

Postmarketing reports: Visual disturbance[Ref]


Common (1% to 10%): Nasopharyngitis, pharyngitis, cough, epistaxis, rhinitis

Postmarketing reports: Dyspnea[Ref]


Common (1% to 10%): Dry mouth, diarrhea, vomiting, constipation, abdominal pain

Postmarketing reports: Nausea[Ref]


Common (1% to 10%): Fatigue, pyrexia, otitis media

Uncommon (0.1% to 1%): Weight increased, asthenia, malaise

Rare (less than 0.1%): Edema

Frequency not reported: Stillbirth

Postmarketing reports: Vertigo[Ref]


Uncommon (0.1% to 1%): Agitation

Rare (0.01% to 0.1%): Aggression, confusion, depression, hallucination, insomnia

Very rare (less than 0.01%): Tic, enuresis

Postmarketing reports: Suicidal ideation, nightmare[Ref]


Very rare (less than 0.01%): Dysuria

Postmarketing reports: Urinary retention[Ref]


Rare (less than 0.1%): Tachycardia

Frequency not reported: Severe hypotension

Postmarketing reports: Palpitation[Ref]


Uncommon (0.1% to 1%): Pruritus, rash

Rare (0.01% to 0.1%): Urticaria

Very rare (less than 0.01%): Angioedema, fixed drug eruption

Frequency not reported: Acute generalized exanthematous pustulosis[Ref]


Rare (less than 0.1%): Hepatic function abnormal, transaminases increased, bilirubin increased

Frequency not reported: Cholestasis

Postmarketing reports: Hepatitis[Ref]


Very rare (less than 0.01%): Thrombocytopenia[Ref]


Rare (0.01% to 0.1%): Hypersensitivity

Very rare (less than 0.01%): Anaphylactic shock[Ref]


Frequency not reported: Glomerulonephritis[Ref]


Postmarketing reports: Appetite increased[Ref]


Postmarketing reports: Myalgia, arthralgia[Ref]

Frequently asked questions

More about Xyzal Allergy 24HR (levocetirizine)

Patient resources

Other brands


Professional resources

Related treatment guides


1. Cerner Multum, Inc. "UK Summary of Product Characteristics." O 0

2. "Product Information. Xyzal (levocetirizine)." UCB Pharma Inc (2007):

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.