Extended release forms of the medication should be swallowed whole, not crushed, broken or chewed. Take a missed dose as soon as possible, unless it is too close to the next scheduled dose. In that case, skip it and take the next scheduled dose. Do not take a double dose. In treatment of motion sickness using dimenhydrinate or diphenhydramine , take the medication at least 30 minutes before beginning travel.
Antihistamines tend to cause drowsiness , while decongestants tend to keep people awake.
The two may or may not offset each other, depending on how you react to the medication. If you drink alcohol while taking these medications, it can make you feel very sleepy , clumsy , or confused . It can impair your ability to drive a car. Avoid drinking while you take this medication. Some antihistamines and decongestants do pass into breast milk .