Antihistamines, often combined with other drugs in cold or sinus preparations, combat the symptoms of allergies. Most are also available in prescription strength doses or in combination with other medicines. Many of the newer prescription medications do not have this side effect. Avoid any antihistamine that makes you drowsy. As these drugs are frequently found in cold and sinus pills, read package labels carefully before taking.
Most pain relievers act by preventing the body's normal inflammatory response to injury or illness.
Prescription strength doses of Tylenol and ibuprofen are frequently combined with a narcotic for more powerful pain relief. Any of the pain relievers that contain narcotics can cause drowsiness and impair judgment, especially if combined with alcohol. Check the ingredients carefully before taking any pain relieving medication purchased while traveling. Motion sickness medications are a class of drugs with which many divers are familiar. Chemically related to antihistamines, seasickness medications can make you drowsy.