Individuals who are using prescription drugs should seek the advice of their personal physician since some medications may induce drowsiness, while others may affect heart rate, blood pressure and circulation. Diuretics, barbiturates and beta-blockers may impair the body’s natural heat loss mechanisms. Anticholinergics such as amitryptaline may inhibit sweating and can predispose individuals to heat rash or to a lesser extent, heat stroke. Some over-the-counter drugs, such as antihistamines, may also cause the body to be more prone to heat stroke.