How Long Does Zyrtec Take to Work? Plus 4 More Zyrtec FAQs
Key takeaways:
Zyrtec (cetirizine) is an over-the-counter (OTC) medication that helps relieve allergy symptoms, such as sneezing and watery eyes. It works by blocking histamine, a substance in the body that can cause these symptoms.
Zyrtec begins to work quickly. Many people start noticing relief within 20 to 60 minutes. And one dose generally lasts for about 24 hours. If needed, you can safely take Zyrtec long term.
Zyrtec is available as a brand-name medication. But you can also find it as a lower-cost generic. If your healthcare professional writes you a prescription for OTC Zyrtec, GoodRx may be able to help you save money.
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Table of contents
If you’re one of the millions of people who have seasonal allergies, you’re likely familiar with antihistamines. This class of medications can help both treat and prevent allergy symptoms. And many are available over the counter (OTC). Zyrtec (cetirizine) is one example.
But how long does Zyrtec take to work? And how long will it last? Below, we answer these plus other frequently asked questions about Zyrtec. That way, you can make an informed decision when choosing the best allergy medication for you.
1. How long does Zyrtec take to work?
Generally, Zyrtec starts working in about 20 to 60 minutes if you take it on an empty stomach. It may take slightly longer (up to 90 minutes) if you take it with food. Zyrtec comes in several dosage forms, and they all take about the same amount of time to start working. This fast-acting property makes it a popular choice for many people looking for quick allergy relief.
2. How long does Zyrtec last?
Typically, one dose of Zyrtec lasts about 24 hours. This makes it a convenient option. A potential exception to this is Zyrtec-D (cetirizine / pseudoephedrine). This product contains both an antihistamine and a nasal decongestant. The recommended dosage of Zyrtec-D is one tablet every 12 hours.
3. How does Zyrtec work?
Zyrtec is an antihistamine. It works by blocking histamine, a chemical in your body that causes allergy symptoms such as sneezing, runny nose, and itching. By blocking histamine, Zyrtec helps lessen these symptoms.
4. Does Zyrtec cause drowsiness?
Yes, for some people Zyrtec can cause drowsiness. But it’s much less likely to do so than older antihistamines such as Benadryl (diphenhydramine).
It’s a good idea to take Zyrtec in the evening until you know how it affects you. And if you find this side effect too bothersome, consider trying a non-drowsy antihistamine. Claritin (loratadine) and Allegra (fexofenadine) are two examples that typically cause less drowsiness than Zyrtec.
Good to know: Combining Zyrtec with other antihistamines or alcohol can increase the chance of drowsiness. Other medications that cause drowsiness, such as benzodiazepines or opioids, can have the same effect when combined with Zyrtec.
5. Can you take Zyrtec long term?
Yes, it’s safe for most people to take Zyrtec long term. In fact, taking an antihistamine every day can help prevent allergy symptoms from starting. So if you’re looking to get ahead of allergy season, consider starting Zyrtec about 2 weeks before you expect symptoms to begin.
Many people worry that they’ll build up a tolerance to antihistamines after taking them for a while. But research suggests this usually isn’t the case. If Zyrtec stops working, it’s unlikely that your body has stopped responding to it. It’s more likely that there’s been a change to the allergens in your environment.
If you feel like Zyrtec has stopped working for you, speak with your medical care team. They may suggest some medication adjustments or perform allergy testing to pinpoint the cause.
How to save on Zyrtec
There are ways to save on Zyrtec, which is available as both a brand-name and generic medication. If your healthcare professional writes you a prescription for OTC Zyrtec, GoodRx may be able to help you save over 80% off the average retail price. Generic Zyrtec’s price at certain pharmacies is as low as $3.16 with a free GoodRx coupon.
The bottom line
Zyrtec (cetirizine) is an over-the-counter antihistamine. It works by blocking histamine, a chemical in the body that can cause allergy symptoms.
Zyrtec typically takes about 20 to 60 minutes to start working and generally lasts about 24 hours. And most people can safely take it long term to help prevent allergy symptoms.
Zyrtec may cause drowsiness for some people. But it’s less likely to make you feel sleepy compared to older antihistamines, such as Benadryl (diphenhydramine). You shouldn’t take Zyrtec with alcohol, other antihistamines, or other sedating medications. Combining them can worsen drowsiness.
Why trust our experts?
References
DailyMed. (n.d.). Search results for: Zyrtec.
MedlinePlus. (2017). Histamine: The stuff allergies are made of.
Naqvi, A., et al. (2023). Cetirizine. StatPearls.
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