When Can You Take Claritin After Taking Benadryl?

Hi there and thanks for reaching out!

Both Benadryl (diphenhydramine) and Claritin (loratadine) are antihistamines and are generally not recommended to take together.

However, Benadryl is fairly short-acting, with effects lasting about 4 to 8 hours after dosing.

In most cases, after taking Benadryl, it would be prudent to wait that amount of time (4 to 8 hours) to take Claritin. There are some exceptions to the above, however, as discussed below.

Taking Claritin And Benadryl Together

Both Claritin and Benadryl work the same way in the body, by blocking histamine-1 receptors.

This prevents histamine from binding to these receptors. When histamine does bind to histamine receptors, it generally produces the symptoms of allergy that we are so familiar with (e.g. runny nose, watery eyes, etc...).

Benadryl

Benadryl (diphenhydramine) is a first generation antihistamine. First-generation antihistamines are known for their sedative effects, which is why they are often included in many over-the-counter sleep medications.

First-generation antihistamines are generally a good option for the initial treatment of allergic reactions, such as from bee stings.

They do a great job to reduce swelling and itching associated with these reactions.

Claritin

Claritin (loratadine) is known as a second-generation antihistamine, most of which do not cause sedation.

They are a good option for the treatment of seasonal allergies as each dose lasts around 24 hours and they don't cause drowsiness.

Using Two Antihistamines Together

Although Claritin isn't associated with drowsiness, adding on Benadryl could potentially increase the risk of sedation.

In addition, and perhaps most importantly, you most likely will not get any additional benefit from using both at the same time.

Each drug has a fairly strong affinity for histamine receptors and taking both may lessen the overall effects of each medication.

The one caveat to the above is that Benadryl may have has better, and quicker effects when it comes to stemming allergic reactions (in some cases).

Benadryl in studies has shown to be more effective in reducing certain types of reactions (wheal and flare reactions) and therefore may provide better relief for hives and inflammation associated with allergic reactions. 

If you are having an allergic reaction, Benadryl is generally okay to take, even if you took Claritin recently. Just be prepared to be a little tired afterward.

As mentioned above, Benadryl is relatively short-acting and the effects should be nearly gone after 4 to 8 hours. In order to avoid the risk of additive sedation, Claritin should be taken at least 4 to 8 hours after Benadryl.