Cetirizine has the fastest onset of action among the newer antihistamines.
Second- and third-generation antihistamines are less likely to cause drowsiness. Of these, cetirizine works the fastest but has a higher chance of making you feel drowsy. Fexofenadine is the least drowsy option.
Cetirizine is the most potent antihistamine available and has been subjected to more clinical study than any other.
“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.
Zyrtec (cetirizine) and Claritin (loratidine) are two popular brands. They contain different compounds but appear to be equally effective. Antihistamines can reduce allergy symptoms, such as watering eyes, itchy skin, hives, and swelling.
Both Claritin® and ZYRTEC® help treat common allergy symptoms. ZYRTEC® starts working at hour 1 on the first day you take it while Claritin® doesn't start working until hour 3.
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. No tolerance has been found to Zyrtec's antihistaminic effect. Once discontinued, the skin recovers its normal reactivity to histamine within three days.
There are multiple kinds of antihistamines, and different antihistamine drugs have different combinations of them. It may be that the active antihistamine in Claritin, loratadine, isn't the kind that's most effective for you. This could cause Claritin to not work well when you take it.
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.
Why do antihistamines stop working? Antihistamines can stop working because your allergies might be getting worse or you might have immune system changes due to aging. You also might not be taking the medication as directed. If you take an antihistamine after being exposed to an allergy trigger, it won't work as well.
Antihistamines and Decongestants
Clarinex (desloratadine), an oral antihistamine, is only available with a prescription. But many other prescription antihistamines are available in both OTC and prescription forms, often at the same strength. The same goes for decongestants.
Astemizole, a new long-acting antihistamine, (H1 receptor antagonist), 10 mg taken once daily was found to be an effective prophylactic treatment for the symptoms of allergic rhinitis in 75% (twelve from sixteen) of subjects in a double-blind placebo-controlled study.
antihistamines that make you feel sleepy – such as chlorphenamine (Piriton), cinnarizine, diphenhydramine, hydroxyzine and promethazine. non-drowsy antihistamines that are less likely to make you feel sleepy – such as acrivastine, cetirizine, fexofenadine and loratadine.
A nonprescription oral antihistamine, such as loratadine (Alavert, Claritin, others), cetirizine (Zyrtec Allergy, others) or diphenhydramine (Benadryl Allergy, others), may help relieve itching. Consider whether you might prefer a type that doesn't cause drowsiness. Ask your pharmacist about options. Apply cold.
Taking an extra dose of Zyrtec by mistake is unlikely to cause serious harm for most people. However, taking a very large amount of Zyrtec can be dangerous. In severe cases, it can cause severe drowsiness, hallucinations, and an elevated heart rate.
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.
Cetirizine is generally very safe. Taking more than the usual dose is unlikely to harm you or your child. If you take an extra dose, you might get some of the common side effects. If this happens or you're concerned, contact your doctor.
Sandoz issued a voluntary recall of 1,023,430 units of Zyrtec (10 mg) capsules as a result of failed impurities and a specification being reported for impurity at the 21-month stability time point, according to an FDA Enforcement Report.
For many people with allergies, symptoms are the worst around 4 a.m. to 6 a.m. Taking an antihistamine at bedtime may help you or your child feel better in the morning during allergy season.
The recommended maximum number of medicines in the 'antihistamines' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'antihistamines' category: Claritin 24 Hour Allergy (loratadine) Zyrtec (cetirizine)
Claritin, Zyrtec, and Allegra are all good antihistamine options and are generally well-tolerated by many people. But there are some differences between them that may make one of these antihistamines better for you than the others. For example, Zyrtec and Allegra may work faster than Claritin.
Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or ...