propranolol
9 interactions related to propranolol
propranolol + melatonin
Propranolol blocks the beta-adrenergic signal the pineal gland uses to make melatonin at night, lowering the body's own nighttime melatonin.
propranolol + st. john's wort
St. John's Wort induces several liver drug-metabolizing enzymes, including CYP1A2 and CYP3A4, plus the transporter P-glycoprotein. Propranolol is cleared mainly through CYP1A2 and CYP2D6, so regular St. John's Wort use can plausibly speed up its breakdown and weaken its effect. Direct studies of this specific pair are lacking; the concern is based on St. John's Wort's confirmed enzyme-inducing action, its documented lowering of theophylline (which shares propranolol's CYP1A2 pathway), and a case report of lost intraocular-pressure control in a glaucoma patient on a topical beta-blocker.
alcohol + propranolol
Alcohol and propranolol can produce additive drops in blood pressure with dizziness, lightheadedness, and fainting through combined vasodilation and a blunted heart-rate response. Propranolol can also mask the racing-heart and shakiness warning signs of low blood sugar, and alcohol can raise propranolol levels in the body.
caffeine + propranolol
Caffeine is a stimulant that nudges heart rate and blood pressure upward, partially opposing the direction propranolol works in. The effect is usually modest, but heavy or concentrated caffeine can blunt propranolol's benefit and worsen the tremor or anxiety it is often prescribed to control.
smoking + propranolol
Cigarette smoking induces hepatic metabolism of propranolol (mainly via CYP1A2 and glucuronidation), increasing its clearance and lowering propranolol blood levels in smokers compared with non-smokers. Nicotine also independently raises heart rate, blood pressure, and circulating catecholamines, partly counteracting propranolol's beta-blocking effect. Both effects reverse when a person quits smoking.
cbd + beta-blockers
CBD weakly inhibits CYP2D6, the liver enzyme that clears beta-blockers such as metoprolol, propranolol, and carvedilol, so in theory it could nudge their plasma levels up. CBD also has a mild blood-pressure-lowering effect of its own. Both actions point in the same direction as the beta-blocker, but the CYP2D6 effect is weak and its real-world clinical significance has not been demonstrated in humans.
energy drinks + beta-blockers
Energy drinks and beta-blockers exert opposing cardiovascular effects: beta-blockers slow heart rate and lower blood pressure, while the caffeine and stimulant load in energy drinks pushes the sympathetic system the other way. This can blunt the medication's effect and, in susceptible people, help provoke an arrhythmia.
coffee + propranolol
Caffeine in coffee acutely raises heart rate and blood pressure, which can partly counteract the heart-rate and blood-pressure-lowering effects of propranolol, a non-selective beta-blocker. Propranolol does not fully block this caffeine pressor response. Older claims that propranolol slows caffeine clearance appear to be wrong: a human study found propranolol slightly speeds caffeine elimination rather than slowing it.
black pepper + propranolol
Piperine, the active alkaloid in black pepper, can inhibit intestinal P-glycoprotein and several liver enzymes that normally limit how much propranolol reaches the bloodstream. A small human study found that concentrated piperine raised propranolol's blood levels, so a stable dose may behave like a somewhat higher one, slightly amplifying its blood-pressure and heart-rate effects. Culinary pepper is not the concern; concentrated piperine supplements are.