Antihistamines and exercise:
Benadryl (diphenhydramine), Claritin (loratadine), and Zyrtec (cetirizine) which are commonly used to treat an allergic reaction have no effect on heart rate and blood pressure during rest and exercise. They also have no effect on exercise capacity. Cold medicine with sympathomimetic agents may increase heart rate or blood pressure during rest and exercise.
Levothyroxine (or brand name Synthroid) and exercise:
This thyroid hormone replacement medication increases heart rate and blood pressure during rest and exercise. It has no effect on exercise capacity except if a patient has angina, it may become worse.