Is It Safe To Take Xyzal Long-Term?

In our latest question and answer, the pharmacist discusses whether or not Xyzal (levocetirizine) is safe to use long-term.


My 13-year-old takes prescription levocetirizine dihydrochloride oral solution (2.5mg/5ml) each day for severe allergies during April and May. They take 10 milliliters once a day. This liquid medication works well. Is it safe for a 13-year-old to be taking this medicine every day for up to 10 to 12 weeks during the height of allergy season in Spring?

Asked by Chuck On May 20, 2019

Answered by
Medical Content Reviewed By PharmacistAnswers Staff

On May 20, 2019
Xyzal Box With Text - Long Term Use Safe?


Yes, the long-term use of Xyzal (levocetirizine), a 'third-generation" antihistamine, is considered to be safe for most people.

In fact, the side effect profile for Xyzal with long-term use is very similar to its side effect profile with short-term use. The prescribing information for the drug states this explicitly:[1]

Long-Term Clinical Trials Experience
In two controlled clinical trials, 428 patients (190 males and 238 females) aged 12 years and older were treated with XYZAL 5 mg once daily for 4 or 6 months. The patient characteristics and the safety profile were similar to that seen in the short-term studies.

Xyzal Prescribing Information

It should be noted that the prescribing information for Xyxal considers 'short-term' use to be up to 6 weeks of exposure to the drug while long-term use is for up to 6 months. Clinical trials evaluating the effects of Xyzal after more than 6 months have not been done.

Xyzal Side Effects

As mentioned, the side effect profile of Xyzal is similar for both short-term and long-term use. Let's take a look at the reported side effects for the drug.

The most common side effects seen in those aged 12 years and older are:

  • Somnolence (sleepiness)
  • Nasopharyngitis (i.e. the common cold)
  • Fatigue
  • Dry Mouth
  • Pharyngitis (sore throat)

The most common side effect seen in those aged 6 years to 12 years are:

  • Somnolence
  • Pyrexia (increased body temperature)
  • Cough
  • Epistaxis (nose bleed)

The side effects listed above were reported to be mild to moderate in severity during clinical trials.

As with most drugs, including Xyzal, rare side effects are seen in clinical trials (but happen at rates equal to, or less than placebo rates) and during post-marketing experience (i.e. after the drug has been on the market).

These rare side effects aren't known to be conclusively caused by a given drug since they happen so infrequently and can't be distinguished from effects caused by other factors.

Nevertheless, rare side effects associated with Xyzal include:

  • Rash
  • Itching
  • Cardiovascular complications
  • Hallucinations
  • Aggression
  • Dizziness
  • Tremor
  • Weight gain
  • Palpitations
  • Visual disturbances

Some of these side effects are associated with overdoses of antihistamines or may be rare complications.[2] I speak more about this in the next section.

Overall though, Xyzal is very well tolerated, in both the short-term and long-term.

To answer your question about whether or not it is safe to use for 10 to 12 weeks specifically, yes, it is for the vast majority of people.

The main side effects (those which occur most frequently) are generally thought to be mild, with tiredness and fatigue being the most common.

Rare Side Xyzal Effects

Xyzal has been associated with several rare side effects (as mentioned above), but a cause-effect relationship isn't known since they occur so infrequently.

Some of them are associated with antihistamine use in general, and not specifically Xyzal. I wanted to touch on them in more detail here.


Cardiovascular side effects are more commonly associated with first-generation antihistamines, like Benadryl or in cases of overdose.[3]

However, the following cardiovascular effects have been reported with Xyzal:

  • Syncope (shortness of breath)
  • Hypotension (low blood pressure)
  • Palpitations

Weight Gain

A slight gain in weight in those aged 12 years and older were seen clinical trials for Xyxal (0.5% incidence rate).

Weight gain has been associated with antihistamines in the past, but overall, it doesn't seem to happen often or to be overly significant.[4]


You may have noticed that a few different infections are listed as side effects for Xyzal.

It does appear that Xyzal may increase the risk of certain types of infection (like a cold). Others have been reported as well (including ear infections and pneumonia)

Although these side effects are rare, be sure to look out for signs of infection in those taking Xyzal long-term, like a fever or cough.


Mood changes have rarely been seen with antihistamine use in general, When seen, they are generally only in pediatric patients (those less than 12).

These effects include:

  • Aggression
  • Agitation
  • Depression
  • Hallucinations

Many of these reactions are known as 'paradoxical excitation' reactions since antihistamines are generally associated with sedation, not excitation. However, it is thought these reactions are quite rare and associated with older, first-generation antihistamines (like Benadryl).[5]


The side effects of Xyzal are similar for both short-term and long-term use (clinical trials up to 6 months in length have been completed). They are generally mild, with the most commonly reported being fatigue and somnolence (sleepiness).

  1. ^ Xyzal Prescribing Information. ClinicalKey
  2. ^ Pharmacology of Antihistamines. PubMed
  3. ^ Cardiovascular safety of antihistamines. PubMed
  4. ^ Association of prescription H1 antihistamine use with obesity: Results from the National Health and Nutrition Examination Survey. PubMed
  5. ^ Paradoxical excitation on diphenhydramine may be associated with being a CYP2D6 ultrarapid metabolizer: three case reports. Natural Standard

About the Pharmacist

Dr. Brian Staiger Pharm.D

Dr. Brian Staiger is a licensed pharmacist in New York State and the founder of He graduated from the University At Buffalo with a Doctor of Pharmacy degree in 2010. He has been featured in numerous publications including the Huffington Post as well as a variety of health and pharmacy-related blogs. Please feel free to reach out to him directly if you have any inquiries or want to connect! He's answered thousands of medication and pharmacy-related questions and he's ready to answer yours! Office: 716-389-3076

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