Caffeine may cause a brief rise in your blood pressure, even if you don't have high blood pressure. This short-term spike in blood pressure happens mainly in people who don't drink caffeine often, rather than in those who do. Still, the blood pressure response to caffeine differs from person to person.
It's not clear why caffeine causes some people's blood pressure to briefly rise. Some researchers think that caffeine could block a hormone that helps keep the arteries widened. Others think that caffeine causes the adrenal glands to release more adrenaline, which causes blood pressure to go up. Stress also might play a role.
People who regularly drink caffeine develop a tolerance to caffeine. As a result, caffeine doesn't have a long-term effect on blood pressure and is not linked with a higher risk of high blood pressure, also called hypertension.
If you have high blood pressure, you likely do not need to limit or stop drinking caffeine if you drink it regularly. But ask your healthcare professional to be sure.
If you don't have high blood pressure, the U.S. Food and Drug Administration says 400 milligrams (mg) a day of caffeine tends to be safe for most adults. But your genes determine how your body breaks down caffeine. So some people can drink more than 400 mg a day and some can drink less before they get side effects. These side effects include:
- Insomnia.
- Heartburn.
- Urinary symptoms.
- Feelings of having a fast-beating, fluttering or pounding heart, also called palpitations.
- Anxiety, in some people.
Keep in mind that the amount of caffeine in coffee, energy drinks and other beverages varies by brand and by the way the drink is prepared.
To see if caffeine might be raising your blood pressure, check your blood pressure before drinking a cup of coffee or other caffeinated beverage and again 30 to 120 minutes afterward. If you don't drink coffee regularly and your blood pressure increases by about 5 to 10 points, you may be sensitive to the blood pressure raising effects of caffeine. If you plan to cut back on caffeine, do so over a few days to a week to prevent headaches from caffeine withdrawal.