Which medications are known to antagonize the effects of antihypertensives?

Decongestants are known to antagonize the effects of antihypertensives primarily due to their mechanism of action. Many decongestants, such as pseudoephedrine and phenylephrine, cause vasoconstriction by stimulating alpha-adrenergic receptors. This vasoconstriction can lead to an increase in blood pressure, effectively counteracting the hypotensive effects intended by antihypertensive medications.

In contrast, antibiotics, antidepressants, and anticoagulants do not typically interfere with the efficacy of antihypertensive drugs in the same manner. While some specific antidepressants may have cardiovascular side effects, they do not directly negate the effects of antihypertensives like decongestants do. Anticoagulants primarily deal with blood coagulation and do not directly affect blood pressure regulation. Antibiotics are mainly used to treat infections and have no impact on blood pressure control. Thus, decongestants stand out as the medication class that actively works against the therapeutic goals of antihypertensives.