Long-term Zyrtec (cetirizine) use can lead to drowsiness, dry mouth, fatigue, and sometimes tolerance (decreased effectiveness), but the most notable risk flagged by the FDA is rare, severe itching (pruritus) that starts days after stopping the medication after months or years of use, often resolving if you restart it. Other potential long-term concerns, though less common, include mild liver issues or weight gain, requiring discussion with a doctor for extended use.
Severe itching may also appear after you stop taking Zyrtec, especially if you've been taking it long-term. Taking Zyrtec long term may also increase your chance of weight gain.
The most common side effect of cetirizine is feeling sleepy and tired. This happens in more than 1 in 10 people. Try a different non-drowsy antihistamine. Make sure you rest and drink plenty of fluids.
While it does not specifically target an organ, its effects are most noticeable in the skin, nose, and respiratory tract, where allergy symptoms typically manifest. Additionally, as with many medications, it is metabolized by the liver and excreted by the kidneys, so these organs are involved in processing the drug.
On May 23, 2025, the FDA issued a warning that patients stopping the oral allergy medicines cetirizine (Zyrtec) or levocetirizine (Xyzal) after long-term use may experience rare but severe itching. These medicines are available in prescription and over-the-counter (OTC) forms.
Be aware, too, that first-generation antihistamines typically are not recommended for adults 65 and older. That's because they have something called anticholinergic properties. Research suggests those properties might raise the risk of dementia.
Fexofenadine (Allegra)
It's one of the least sedating second-generation antihistamines, making it a safe option for long-term use if you take it as your doctor prescribes.
The pseudoephedrine in Zyrtec-D can raise your blood pressure or heart rate. The longer you take pseudoephedrine, the more likely it is you'll experience these side effects. That's why you should only take oral decongestants for up to 7 days in a row without a healthcare professional's OK.
Zyrtec interactions at a glance
The first symptoms of antihistamine withdrawal typically begin within two to four after you stop taking the medication. Once symptoms have begun, they are likely to intensify over the next three to five days. After peaking, these symptoms should begin to slowly subside over the following week.
Side effects of antihistamines
The FDA now requires a warning on Zyrtec (cetirizine) and Xyzal (levocetirizine) about severe itching that can happen after stopping the medication. This side effect is rare, but it becomes more likely with long-term use. Slowly reducing your dose (tapering) instead of stopping it all at once may help prevent itching.
The basic version is mainly for classic allergy symptoms such as runny nose and sneezing – the only medicinal ingredient they contain is called an antihistamine. Examples of these are Allegra, Claritin, and Zyrtec. These will not affect your blood pressure at all.
Is it okay to take ZYRTEC® over a long period of time? The ZYRTEC® package label doesn't state a limit on how long you can take ZYRTEC®. Talk to your doctor if you have any questions, especially if you're taking other medicines or being treated for any other conditions.
A study has shown that Zyrtec (generic name: cetirizine) is associated with weight gain if taken over the long-term. This may occur because antihistamines can block histamine-1 (H-1) receptors which will increase your appetite.
If you're using oral antihistamines very often, you might have wondered if it's OK to keep relying on antihistamines to control symptoms of allergies. The good news is there's no research evidence to suggest regular, long-term use of modern antihistamines is a problem.
Alcohol's Impact: Consuming alcohol affects coordination, judgment, and poses risks such as liver disease and cancer. Combining Zyrtec and Alcohol: This can heighten drowsiness, sedation, and impair mental function. Healthcare Advice: Experts caution against mixing Zyrtec with alcohol to avoid amplified side effects.
Facts about Cetirizine and Levocetirizine
These medicines are available as tablets or solution taken by the mouth once daily. Common side effects of cetirizine and levocetirizine include fatigue, drowsiness, sore throat, cough, dry mouth, nosebleed, fever, diarrhea, and vomiting.
Cetirizine is unlikely to do you any harm if you take it for a long time. However it's best to take it only for as long as you need to. If you take it regularly over a long period there's a very small chance of severe itching if you stop treatment suddenly.
In summary, cetirizine after single oral doses of 10 mg and 20 mg was found to impair speed of memory scanning and critical tracking, which may be due to common effects on speed of central processes.
Non-drowsy oral antihistamines, such as Claritin (loratadine), are also safe options. Nasalcrom (cromolyn) nasal spray and antihistamine eye drops, such as Zaditor (ketotifen) are also safe for older adults.
Who Should Not Take Zyrtec. Speak with your healthcare provider before using Zyrtec if you are pregnant, trying to become pregnant, or breastfeeding. Zyrtec should not be taken with alcohol or marijuana. Doing so can increase the risk of drowsiness and can make driving or handling heavy equipment hazardous.
ISSUE: The FDA is warning that patients stopping the oral allergy medicines cetirizine (Zyrtec) or levocetirizine (Xyzal) after long-term use may experience rare but severe itching. These medicines are available in prescription and over-the-counter (OTC) forms.
Slowly tapering off Zyrtec may help lower the risk of developing withdrawal symptoms, such as intense itching. This is because it allows your body some time to adjust, which may help reduce symptoms. If you're taking Zyrtec and wish to stop it, consider speaking with a healthcare professional.
First generation antihistamines, while very effective at controlling symptoms, are often associated with symptoms in older adults such as anxiety, confusion, sedation, blurred vision, reduced mental alertness, urinary retention and constipation.