Both syncope due to cardiac arrhythmias and syncope due to orthostatic hypotension can be the result of medication. Medications that lead to bradycardia, such as beta blockers, or tachyarrhythmias, such as sodium channel blockers, or medications that prolong the QT interval may cause syncope. In addition, orthostatic hypotension may occur in the setting of antihypertensives, peripheral vasodilators, diuretics, phenothiazines, and antidepressants. The orthostatic effects are particularly strong with volume depletion, dehydration, or exposure of elderly individuals to dry, hot weather. Alcohol and other illicit drugs may lead to syncope via both arrhythmias and orthostatic hypotension.