As pleurisy root and other plants in the Aesclepius genus contain cardiac glycosides, it is best to avoid use of pleurisy root with heart medications such as beta-blockers.

Three kidney transplant patients developed hyperkalemia (high blood potassium levels), a potentially dangerous condition, following intravenous administration of labetalol. Additional research is needed to determine whether taking oral labetalol together with potassium supplements might also lead to elevated blood levels of potassium. However, some other beta-blockers (called “nonselective” beta-blockers) are known to decrease the uptake of potassium from the blood into the cells, leading to hyperkalemia. People taking beta-blockers should therefore avoid taking potassium supplements, or eating large quantities of fruit (e.g., bananas), unless directed to do so by their doctor.