Yes, Zyrtec (cetirizine) can cause fatigue or sleepiness, even though it's considered a "non-drowsy" antihistamine, and for some people, it can be significant enough to feel like extreme tiredness, especially at higher doses or when combined with alcohol or other sedatives. While generally less sedating than older antihistamines, feeling sleepy is a common side effect for more than 1 in 10 users, and it's important to see how it affects you before driving or operating machinery.
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.
Allegra has no sedative effect, even at high doses. Claritin and Clarinex have no sedative effect at recommended doses. But they have a low sedative effect at higher-than-recommended doses. Zyrtec has a low sedative effect at recommended doses and a moderate sedative effect at higher-than-recommended doses.
' It really depends on which type of glaucoma you have. Antihistamines and decongestants generally have no effect on open-angle glaucoma — the most common form of the disease. But people with closed-angle glaucoma, also called narrow-angle glaucoma or angle-closure glaucoma, should avoid or use them with caution.
For allergies, don't use under 2 years of age. Reason: not FDA approved. For age 2 - 6 years, talk with your child's doctor before using. For colds, not advised at any age.
Common side effects of cetirizine and levocetirizine include fatigue, drowsiness, sore throat, cough, dry mouth, nosebleed, fever, diarrhea, and vomiting.
While less common, Zyrtec can sometimes cause mood changes, such as agitation, anxiety, or mood swings. Hallucinations and suicidal thoughts can also happen in rare cases. If you notice a change in your behavior (or your child's) after taking Zyrtec, it's best to stop taking it and seek medical care.
have kidney failure. have epilepsy or another health problem that means you're at risk of having seizures or fits. have a condition that means you have difficulty peeing. are due to have an allergy test – taking cetirizine may affect the results, so you might need to stop taking it a few days before the test.
Acute angle-closure glaucoma
If you're taking antihistamines or decongestants to ease seasonal allergies or sinus congestion, you might notice your eyes feeling dry, irritated, or even blurry. These common medications work by reducing the fluid your body produces, including tears that keep your eyes moist and comfortable.
If it makes you sleepy, the side effect will have likely worn off by the time you wake up, and since the medication can provide relief for 24 hours, you'll still experience relief during the day.
To avoid daytime drowsiness, take an antihistamine in the evening rather than in the morning. It may help you sleep, with drowsy effects wearing off by the next morning. Be aware that drowsiness can last longer than you might expect – and that some antihistamines can cause vivid dreams.
Cetirizine is a second-generation antihistamine that crosses the blood–brain barrier, has been previously associated with insomnia and nocturnal awakenings, and can cause tolerance with long-term use. Cetirizine has very rarely been associated with either the onset or exacerbation of sleep terrors.
Zyrtec can make you tired because it blocks histamines in your body, which help with alertness. While it's less likely to cause drowsiness than older antihistamines, it can still affect some people this way.
Allergy fatigue results from the immune system overreacting to allergens. Allergy fatigue is an intense sense of tiredness and lack of energy often associated with the body's reaction to allergens. This feeling of exhaustion is not merely a result of poor sleep quality due to common allergy symptoms.
Fatigue, drowsiness
Consider these strategies: Take a brief nap during the day. Get some physical activity, such as walking. Avoid driving or operating dangerous machinery until the fatigue passes.
Stage 1: Glaucoma begins with any alteration to your drainage system, which leads to increased intraocular pressure.
Halos around lights: Rainbow-like rings around lights, especially at night, can be a red flag. Eye pain or pressure: A dull ache or intense pressure may signal acute glaucoma.
What is pre-glaucoma? Pre-glaucoma is a term used for patients with ocular hypertension (persons with elevated intraocular pressure but no detectable disc or visual field damage), and patients with large cup/disc ratios and normal visual fields who may or may not have early normal-tension glaucoma.
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.
Yes, cetirizine (Zyrtec) can make you sleepy or drowsy, though it's considered a less sedating antihistamine compared to older ones, with drowsiness being a common side effect in over 10% of people, often mild and temporary. It's important to see how it affects you before driving or operating machinery, and avoid alcohol, which can increase sleepiness.
Elimination: The mean elimination half-life in 146 healthy volunteers across multiple pharmacokinetic studies was 8.3 hours and the apparent total body clearance for cetirizine was approximately 53 mL/min.
The "3-day rule" for allergens means introducing one new allergenic food at a time and waiting 3 to 5 days before introducing another, allowing parents to easily pinpoint which food caused a reaction, though some experts suggest a shorter wait (2-3 days) or even daily introduction for non-high-risk infants, while emphasizing introducing common allergens like peanut, egg, dairy, soy, wheat, tree nuts, and fish early (around 6 months) and regularly (2-3 times a week) to build tolerance and prevent allergies, always starting with tiny amounts and monitoring for signs like hives, swelling, or breathing issues.
Diphenhydramine is a first-generation antihistamine that crosses into the brain easily. It's well known for causing sleepiness and sometimes confusion. Its strong anticholinergic effects make it more likely to interfere with memory and attention.
Some antihistamines have been known to cause hallucinations, delusions, and trouble sleeping in extreme cases. People who take antihistamines regularly may build up a tolerance to the drug, which means they need to take higher and higher doses to get the same effect. This can lead to addiction.