 [ Symptoms ] if i am feeling really hungry after exercising what is the best thing to eat after a workout  and i am a guy not sure if that matters [ Disease ] it is usually not necessary to take two antihistamines on the same day but there are exceptions claritin is given once per day but depending on the time you took it it could be wearing off around bedtime for instance since benadryl can be very sedatiing and only lasts for about 4 hours a person could take it even though the claritin was still on board