You have high blood pressure, which you keep under control by taking medications. Is it safe to soak your cares away in your hot tub or work up a sweat in your sauna? Doctors say yes—but with reservations. Hot tubs and saunas are generally considered safe for people with high blood pressure, so long as you take certain precautions. If you have other serious medical conditions in addition to your high blood pressure, such as heart disease, you need to be especially careful. Here’s a guide to the risks and precautions involved in using hot tubs or saunas if you have high blood pressure. Why Hot Tubs and Saunas Can Be Dangerous Several potential complications can occur from overexposure to hot tub or sauna heat, especially if you also have cardiovascular disease. You could experience either blood pressure that's too low (which could cause you to pass out) or too high, depending on the condition of your heart, arteries and blood vessels and how they respond to your heat exposure. Heat can cause your blood vessels to dilate, which lowers your blood pressure and, as a consequence, requires your heart to work harder—to beat faster—to make up the difference. This can overtax an unhealthy heart. Other symptoms you could experience include dizziness, faintness, nausea or an irregular heartbeat. You might not have enough blood flowing to your heart or your body in general. You could even have a heart attack. Hot tubs and saunas may also interact with your high blood pressure medications. Diuretics, for example, are commonly prescribed but cause loss of fluid and salt; if you are overheating in a hot tub or sauna, you are already losing fluid, so you may be more likely to become dehydrated. If you’re taking medication for high blood pressure, check with your doctor to see if this extreme heat is safe for you. Five Key Precautions to Keep in Mind Despite the potential risks, you can still enjoy using a hot tub or sauna—so long as you follow commonsense precautions. Here are a few to keep in mind: If your doctor has told you to avoid moderate exercise, check before using a hot tub or sauna. The physical effects from this type of heat on your body are similar to what you get from a brisk walk and may be too taxing for your body. Don’t use a hot tub or sauna if you are experiencing extremely high blood pressure (higher than 180 for the top number or 110 for the lower number). This is considered a hypertensive crisis and you should seek immediate medical help. Use the hot tub or sauna for a brief time only—about 10 to 15 minutes per session. This is especially important if you have heart disease. Also avoid extremely hot temperatures. Don’t drink alcohol before or while hot-tubbing or enjoying a sauna. Doing so could make you drowsy and more likely to lose track of time. You also could get dizzy when you get out, which raises your risk of falls or fainting. Avoid moving quickly back and forth between very cold and very hot environments, such as jumping from cold lake to steaming hot tub and back again. This can cause swings in your blood pressure and be hard on your system. Ask a companion to accompany you to the hot tub or sauna. The seriousness of all risks previously described intensifies if you are alone. How Hot Tubs and Saunas May Help Lower Your Blood Pressure Several small studies have shown that both saunas and hot tubs can lower blood pressure, at least for a few minutes. One Canadian study in 2003 compared a group of 21 men and women with high blood pressure that was controlled by medication and a group of 23 who didn't have hypertension. Both the groups experienced a small drop in their top (systolic) blood pressure during their 10-minute time in the hot tub; their pressure returned to baseline about 10 minutes after getting out of the tub. Other studies have looked at the benefits of infrared saunas for hypertensive and cardiac patients. An infrared sauna is one that heats your body with light rays, compared to a traditional sauna that heats the air around you by woodstoves or electric heaters. Infrared saunas don't get as hot as traditional ones, but because of the way the infrared heat penetrates your body, you sweat more. Your blood vessels also dilate, which can lower your pressure. A 2009 review of studies about the effect of infrared saunas found "limited moderate evidence" that infrared sauna use helped normalize blood pressure. No negative side effects had been reported. The bottom line is that it's usually OK to heat up in a hot tub or sauna even if you have high blood pressure—but you need to do so with care. Call your doctor before enjoying these activities to make sure they’re safe for you.