No, it is generally safe for most people to take Zyrtec (cetirizine) every day for long-term allergy symptom control, provided you follow the recommended dosage and have consulted with a healthcare professional. Zyrtec is a second-generation antihistamine, which are specifically designed for ongoing use and are less likely to cause significant side effects than older, first-generation antihistamines.
These medicines can cause constipation by blocking the movement of gut muscles. Examples include oxybutynin (Ditropan) and tolterodine (Detrol) for urinary incontinence and diphenhydramine (Benadryl), fexofenadine (Allegra), loratadine (Claritin), and cetirizine (Zyrtec) for allergies.
It is not recommended to take both together. Taking both together can increase the risk of side effects, such as drowsiness, dry mouth, dry eyes, blurred vision, urinary retention, and constipation. It is unnecessary to take both together because of their similarity.
You can take antihistamines daily to help manage your symptoms and reduce your reaction.
Some medicines, including those for allergies like antihistamines and steroids (prednisolone), can cause acne breakouts.
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.
Common symptoms may include:
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.
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.
How long do you need relief? Some over-the-counter medications, including Claritin, Allegra and Zyrtec, provide 24-hour relief, so you only need to take them once a day as needed. These allergy medications all begin working within a few hours and can safely be taken long-term.
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.
Don't quit cold turkey: try a tapering dose instead
A simple step-by-step could look like this: Step 1: Reduce your daily dose by half for about a week. Step 2: Move to taking the lower dose every other day for another week. Step 3: After that, stop entirely or begin your new antihistamine.
Xyzal (levocetirizine) and Zyrtec (cetirizine) are antihistamines used to relieve allergy symptoms such as sneezing, runny nose, itchy eyes, and hives. 1 Although Xyzal and Zyrtec work similarly, some people prefer Xyzal because it's less likely to cause drowsiness.
To empty your bowels quickly, try drinking warm coffee or water, using a squatting position with a footstool for better posture, gently massaging your abdomen in a downward motion, or using a suppository or enema for faster results; these methods stimulate the digestive system or physically help clear the colon.
Diabetics can safely take most over-the-counter antihistamines for allergies, such as cetirizine (Zyrtec), fexofenadine (Allegra), and loratadine (Claritin). Nasal sprays like fluticasone (Flonase) are also safe. However, they should avoid decongestants, which can raise blood sugar levels.
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.
These are some examples of prescription allergy medicines:
The optimal way to avoid these problems is to use antihistamines with the highest level of cardiovascular safety, e.g. bilastine, which does not affect the CYP3A4 isoenzyme, nor the QT interval, even when overdosed.
Alcohol can increase the nervous system side effects of cetirizine such as dizziness, drowsiness, and difficulty concentrating. Some people may also experience impairment in thinking and judgment. You should avoid or limit the use of alcohol while being treated with cetirizine.
Antihistamines, which are commonly used to treat symptoms such as a runny nose or sneezing, are generally safe for patients with abnormal heart conditions. However, the FDA has warned that antihistamines taken in conjunction with some high blood pressure medications may cause a spike in blood pressure.
Some antihistamines you only take once a day. Others, you can take more than once a day. How long you can take it: You can take some types of antihistamines long term. But others are only for short-term use (a few days).
Corticosteroid sprays, also called glucocorticoid sprays, prevent and relieve nasal allergy symptoms. These medicines are very effective on their own for treating ongoing or seasonal hay fever.
Vitamin B 6: Often there is a deficiency
In studies and in practice, it was found that many affected people have histamine intolerance, a vitamin B6 deficiency. Some sources state that vitamin B6 is required for the synthesis of the enzyme dao and is involved in the breakdown process of histamine.
A blood histamine test must be collected rapidly, as soon as symptoms develop. Instead of a blood test, a histamine test performed on urine collected over a 24-hour period may be ordered instead to evaluate histamine production over a longer time frame.
A histamine dump can feel like an overwhelming wave of symptoms, often sudden and intense. For example, individuals may experience flushed skin, rapid heart rate, and intense itching all at once. At night, this can disrupt sleep and leave a person feeling fatigued and anxious the next day.