Can You Take Claritin In The Morning And Zyrtec At Night?

Answer

Thanks for reaching out to us. Yes, you could certainly take one antihistamine in the morning, and one in the evening, but you have to consider that all of the drugs you mentioned in your question (Claritin, Zyrtec, Allegra), are second-generation antihistamines, and can be dosed every 24 hours.

These antihistamines are available in lower dosages that are indicated for twice-daily dosing (e.g. Claritin has a 5mg dose that is indicated to be dosed every 12 hours versus the 10mg dose that is taken every 24 hours), so what you are proposing can be done (switching antihistamines every 12 hours).

However, I'm not sure this would be the most effective way to help with your allergies. Are you finding that your antihistamine wears off before 24 hours and that's why you want to switch to another 12 hours later?

Although these antihistamines are distinct drugs, they work the same way (bind to the H1-receptor) and you may simply be better off taking a 24-hour version of just one. Additionally, there are cases where higher than usual doses may be recommended by your doctor, and studies show these higher doses can be safe and effective (such as this study and this study).

Other Options

So, as stated above, you can take 12-hour versions of the antihistamines in question:

• Claritin (loratadine) 5mg every 12 hours
• Allegra (fexofenadine) 60mg every 12 hours
• Zyrtec (cetirizine) 5mg every 12 hours

Alternatively, you can simply take the 24-hour version of the antihistamines, and dose once daily:

• Claritin (loratadine) 10mg every 12 hours
• Allegra (fexofenadine) 180mg every 12 hours
• Zyrtec (cetirizine) 10mg every 12 hours

There may be cases where your doctor recommends taking higher than the usual doses every 24 hours, or even combining two antihistamines, and studies have shown this can be safe and effective for severe allergies/itching. You may be at a slightly higher risk of some side effects, like dizziness and drowsiness, but overall, antihistamines are well tolerated even at higher than usual dosages.

Lastly, another good alternative is to combine an oral antihistamine with a nasal steroid (e.g. Flonase, Nasacort, Rhinocort). Studies show that nasal steroids are more effective than antihistamines for allergy symptoms, and the combination of both can provide even greater benefits.

About Second-Generation Antihistamines

 Both Zyrtec and Claritin are considered "second-generation" antihistamines.

They block histamine in the GI tract, blood vessels, and lungs to aid with mild allergic reactions, typically seasonal allergies. Second-generation antihistamines are generally non-drowsy but, Zyrtec has been reported to cause sedation in about 10% of individuals who take it. Claritin and Allegra, on the other hand, are considered and marketed as non-drowsy.

Second-generation antihistamines are often used over "first-generation" antihistamines, such as Benadryl because they have milder side effects. Typically, these antihistamines do not produce the same drowsiness and sedation that Benadryl is known for and allow patients to take them at any time of the day without feeling sleepy and potentially confused.

Second-generation antihistamines are also ideal for treating seasonal allergies because they are dosed once a day. Based on studies of how these drugs work in the body when taken at the recommended dose, their effects have been seen to be maintained for over 24 hours.

 Antihistamines can be combined with other drugs as well, such as nasal decongestants (e.g. Sudafed) and nasal steroids for better relief of symptoms. 

Final Words

Thanks so much for reaching out! I really hope you found this answer helpful!