Never take a new drug for the first time right before diving. And if any medication makes you feel antsy, nervous, sleepy or disoriented, don't dive while taking it, even if it's considered safe. Decongestants shrink inflamed nasal and sinus membranes, opening these passages so that air can pass more easily. Because they can make equalizing easier, decongestants are commonly used by divers. Steroids are also becoming more popular to relieve the symptoms of stuffy nose and sinuses that are caused by allergies.
Reverse squeeze can occur if the drug wears off during the dive.
Make sure that you have used the medication on land before using it while diving. 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.