What effect does Caffeine in Coffee have on high blood pressure?

There have been several clinical studies into the effects of coffee and caffeine on blood pressure, these studies have shown rather inconsistent results. Drinking a regular amount of coffee, say 2 - 4 cups a day, may raise blood pressure slightly. Respected agencies including the Food and Drug Administration, the National Academy of Sciences and the U.S. Surgeon General’s office have stated that caffeine carries no health risks.

Drinking one or two cups of coffee raises the blood pressure by about 5 mm Hg. Any such effects are not permanent, passing within a few hours. This is because, unlike alcohol or smoking, caffeine doesn't accumulate in the body. Some people who drink coffee regularly can develop a tolerance to it, such that they no longer notice any effects even after several cups of coffee.

If you have high blood pressure and drink a lot of coffee, the results of studies suggest that if you stop drinking coffee (or possibly switch to decaffeinated) you may experience a slight fall of your blood pressure, but don’t expect a dramatic change.

Caffeine is a mild stimulant and there is therefore reason to expect that drinking larger amounts of coffee and other high caffeine drinks might lead to a rise in blood pressure. But, caffeine is only a very mild stimulant, and as mention above, passes through the body quite quickly. Caffeine is also self-limiting, because it acts on the kidneys to raise the rate of its own excretion.

Whatever caffeine's effects on blood pressure, the important thing about coffee drinking is that it has not been found to be associated with any increased mortality from heart attacks or strokes.

For most people moderate drinking of coffee (4 - 5 cups per day) is considered perfectly safe. Thats about 400mg of caffeine. Pregnant women should stay below 300mg of caffeine per day. (Remember that caffeine can be found in other products like Tea, Cola, Sports Energy Drinks and Chocoalte.)

Don't Smoke and Drink Coffee

Caffeine can be a mild central nervous system stimulant. Drinking coffee can also add to the blood pressure-raising effect of other stressors. If you drink coffee with a cigarette, your blood pressure may increase by more than 10 mm Hg over the next hour or two, and coffee also exaggerates the response to mental stress.

Occupational stress + caffeine = elevated blood pressure

So, if you have been diagnosed with high blood pressure (hypertension) you should avoid coffee and caffeine if you're stressed.

People in stressful jobs who need to stay alert will often drink strong, high caffeine coffee. If you have high blood pressure you should avoid the combination of caffeine and stress. Especially if you also smoke!

Is Coffee Dehydrating?

Coffee in moderate amounts is not dehydrating, and cannot raise your blood pressure because of dehydration. (see our blood pressure diet home page for info on the theory that dyhration can increase your blood pressure)

Is Caffeine Addictive?

Again, in moderate amounts, there's no evidence that caffeine carries a risk of addiction.

More than Coffee and Blood Pressure

We hope you've found the information about coffee and blood pressure useful. If you also drink alcohol, then please take a look at the pages about alcohol and blood pressure as alcohol can have a greater affect on blood presssure than small amount of caffeine.