Hot Tubs: How Safe Are They?

A soak in a hot tub could be just the thing to relax you after a long day. The warm, bubbly water also eases aches and pains from conditions like arthritis, low back pain, and fibromyalgia.

But hot tubs might not be safe for some people, including pregnant women and those with heart disease. And when they aren’t cleaned well, they pose risks to even healthy people.

Before you buy a hot tub for your backyard or step into those warm waters at the spa or gym, make sure you know a bit about their safety.

Health Benefits

Warm water soothes your body for a few reasons. The heat widens blood vessels, which sends nutrient-rich blood throughout your body. Warm water also brings down swelling and loosens tight muscles. And the water’s buoyancy takes weight off painful joints.

A dip in the hot tub might also help your mental state. Research shows they can promote relaxation and ease stress.

Hot Tub Risks

These warm water whirlpools can pose some risks if you're not careful.

Infections

Between 2000 and 2014, outbreaks from treated pools and hot tubs were linked to more than 27,000 infections and eight deaths in the United States. When hot tubs aren't cleaned well, their moist environment is the perfect breeding ground for bacteria.

Pseudomonas, one type of bacteria that thrives in hot tubs, causes infections of the hair follicles and skin. Symptoms include red, itchy bumps on the belly and areas covered by your bathing suit. These bumps can pop up anywhere from a few hours to a few days after you take a dip. The same bacteria cause an infection known as swimmer's ear.

Other germs that live in hot tubs can also make you sick. Cryptosporidium causes GI infections with diarrhea. Legionella causes a severe type of pneumonia, or lung disease.

Hot Tub Use in Pregnancy

Hot tubs might not be safe for pregnant women because they increase body temperature. Research finds that pregnant women who use a hot tub more than once or for long periods of time are more likely to have babies with neural tube birth defects like spina bifida or anencephaly.

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Avoid hot tubs if you can during those 9 months. If you do use a hot tub, turn down the temperature and limit your time in the water to less than 10 minutes.

Heart Risks

Be cautious when using a hot tub if you have heart disease. When you soak in hot water, your body can't sweat. Your blood vessels instead need to widen to cool you off. This makes your blood pressure drop. In response to falling blood pressure, your heart rate speeds up.

This isn't a problem for healthy people, but if you have heart disease, it can strain your heart.

Hot Tub Safety Tips

To stay safe, follow these tips:

Ask your doctor. If you're pregnant or you have a health condition like heart disease, ask your doctor if it's safe for you to get into a hot tub.

Check the cleanliness. Ask the hotel or gym how often they clean their hot tub, and whether they keep the pH and chlorine concentrations at levels the CDC recommends (a pH of 7.2-7.8, and a free chlorine concentration of at least 3 parts per million). If the water looks murky or slimy, don't get in.

Avoid crowds. Stay away when a hot tub is full. More people equals more germs. About half of people say they don't shower before they swim.

Turn down the heat. A temperature of 100 F should be safe for healthy adults. Anything over 104 could be dangerous. Turn it down another couple of degrees if you have a medical condition.

Limit your time. Don't stay in the hot tub for longer than 10 minutes. If you feel dizzy, overheated, or unwell, get out right away.

Watch where you sit. Don't sit too close to the heat source. Keep your head, arms, and upper chest out of the water to avoid overheating, especially if you're pregnant.

Stay hydrated. Drink water while in the hot tub to cool off your body. Avoid alcohol, which can dehydrate you.

Don't go from hot to cold. Don't jump straight from the hot tub into the pool to cool off. The cold water could shock your system and spike your blood pressure.

Wash off afterward. Take off your bathing suit and shower with warm water and soap as soon as you finish.

WebMD Medical Reference Reviewed by Carol DerSarkissian on June 11, 2019

Sources

SOURCES:

American Osteopathic College of Dermatology: "Hot Tub Folliculitis."

Arthritis Foundation: "Warm Water Works Wonders on Pain."

Birth Defects Research: "Maternal use of hot tub and major structural birth defects."

CDC: "Facts About 'Hot Tub Rash.' "

Cleveland Clinic: "Hot Tubs Can Land Your Heart in Hot Water."

Evidence-Based Complementary and Alternative Medicine: "Physical and Mental Effects of Bathing: A Randomized Intervention Study."

Harvard Medical School: "Ask the doctor: Hot tubs and heart health."

Mayo Clinic: "Is it safe to use a hot tub during pregnancy?"

Morbidity and Mortality Weekly Report: "Outbreaks Associated with Treated Recreational Water -- United States, 2000-2014."

Pool & Hot Tub Alliance: "Would You Know If Your Local Pool Failed Its Health Inspection? Unlikely, Survey Reveals."

United States Consumer Product Safety Commission: "CPSC Warns of Hot Tub Temperatures."

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