Claritin doesn’t cross the blood-brain barrier, so it’s unlikely to make you drowsy, she says. It also takes a bit longer to ...

Vets sometimes choose Claritin because it won’t cause drowsiness and lasts longer than some other kinds of antihistamines.

loratadine (Claritin) These newer antihistamines are less likely to cause drowsiness and dizziness. Research has found them less likely to cause dangerous effects if a person takes too much.

On non-drowsy formulas, look for stimulants such as the decongestant pseudoephedrine (like Claritin D, above) and caffeine, which could keep you awake at night. What it means: "PM" formulas ...

Allegra is the least likely to make you drowsy. Claritin is long-acting, with effects that last for 24 hours. Zyrtec acts the fastest - usually within one hour - but is also the most likely to ...