But if taken every day, they can also help prevent symptoms from starting. The American Academy of Otolaryngology–Head and Neck Surgery (AAO-HNS) currently recommends those taking antihistamines for allergies to take them every day — instead of only when symptoms flare up — to maximize their benefits.
Depending on your symptoms, you can take antihistamines: Every day, to help keep daily symptoms under control. Only when you have symptoms. Before being exposed to things that often cause your allergy symptoms, such as a pet or certain plants.
Response and effectiveness. Peak concentrations are reached within one hour of administration of Zyrtec tablets or syrup. The onset of effect occurs within 20 minutes in 50% of people and within an hour in 95%. Effects persist for at least 24 hours following a single dose of Zyrtec.
However, Zyrtec does occasionally have some side effects, the most common of which are drowsiness, dizziness, fatigue, and headaches. There have been reports, through few studies, of withdrawal symptoms in people attempting to stop taking Zyrtec. These people report unbearable pruritus (itching) and/or hives.
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.
Cetirizine is unlikely to do you any harm if you take it for a long time. However it's best to take cetirizine 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.
One study has reported a more serious long-term effect, a 3.5-fold increase in the risk of gliomas, a common type of brain tumor in patients with long-term antihistamine use for allergic conditions.
"When taken in the recommended doses, antihistamines can be taken daily. This is especially true with Zyrtec, since it doesn't show decreasing effectiveness if used daily," says Sima Patel, MD, an allergist at New York Allergy & Sinus Centers.
Dr Grant confirms that many people can suffer withdrawal symptoms if they stop taking antihistamines suddenly. Dr Grant recommends the patient resume taking the antihistamines and then slowly reduce the dose to wean off slowly.
Some people report that if they stop such antihistamines suddenly, they can experience levocetirizine (Xyzal) and cetirizine (Zyrtec) withdrawal itching.
Cetirizine can be taken at any time of the day. In most people it is non-sedating, so they take it in the morning. However, a percentage of people do find it to be sedating so if it does make you drowsy it is best to take it in the evening. Cetirizine can be taken with or without food.
Zyrtec may interact with other medicines that make you sleepy (such as other cold or allergy medicine, narcotic pain medicine, sleeping pills, muscle relaxers, and medicine for seizures, depression, or anxiety).
ZYRTEC® Allergy Dye-Free Chewables
Adults and children 6 years and older Chew and swallow 2 tablet (10 mg) once daily; do not take more than 1 tablet (10 mg) in 24 hours. A 5 mg product may be appropriate for less severe symptoms. Adults 65 years and over Ask a doctor.
In general, wean gradually by 25-50% of the daily dose every 1-4 weeks. If reason for deprescribing is serious adverse effects, wean faster or cease immediately.
Allergists recommend long-acting, non-sedating antihistamines — ones that won't make you sleepy — for everyday use. Though you may know them by their brand names, the generic versions tackle the same problems: Cetirizine (Zyrtec®, Aller-Tec®, Wall-Zyr®).
In some cases, over the counter allergy meds stop working because your body has built up a resistance to your usual remedy. However, it is far more common for other changes in your life or your body to be the culprit behind the change and your OTC allergy relief not giving you the results you are used to.
When antihistamines block histamine, our appetite can increase. This, plus side effects like drowsiness, could lead to weight gain. Your risk of gaining weight from antihistamines may depend on many factors. But a healthy diet, physical activity, and other lifestyle factors can help you manage your risk.
Some people have found that switching to a different antihistamine such as fexofenadine (Allegra) or loratadine (Claritin) can ease the itching from cetirizine withdrawal.
Long term use of some antihistamines may increase your risk of dementia. Diphenhydramine (Benadryl®) blocks the effects of a neurotransmitter called acetylcholine. This neurotransmitter is vital for memory and learning.
Claritin and Zyrtec are popular over-the-counter antihistamines. Doctors consider them safe and effective treatments for minor allergies. Both are second-generation antihistamines. These cause less drowsiness than first-generation antihistamines.
Cetirizine and levocetirizine have been linked to rare, isolated instances of clinically apparent acute liver injury.
“Claritin is a 24-hour antihistamine that works in the same way as Zyrtec, however, research has found that Claritin may be less potent than Zyrtec and therefore less effective,” explains Dr. Parikh. Although potential side effects may also be minimized as a result, she adds.
The evidence presented does suggest, however, that patients on prolonged antihistamine therapy may develop clinical tolerance. When this is suspected the dose should be increased or the drug discontinued for a short perior (3 to 14 days) before resuming therapy.