The short answer
For most healthy adults, saunas are very safe. In Finland, where most people take one weekly, deaths in saunas occur at fewer than 2 per 100,000 people a year, and half involve alcohol. The main risks are fainting, dehydration and overheating. People with some heart conditions, pregnant women and anyone who has been drinking need extra care.
On this page
How risky are saunas?
Not very, for most people. A Finnish study looked at every death that happened in a sauna in Finland from 1990 to 2002, in a country with around two million saunas. The rate was under 2 deaths per 100,000 people a year. About half were natural deaths, mostly from existing heart disease, and a quarter were caused by heat. Half of all the people who died had been drinking alcohol.
A systematic review of 40 clinical studies of regular dry saunas, with 3,855 participants, found only one reported harm: a reversible drop in sperm production in a study of ten men.
What are the main risks?
- Fainting, usually on standing up after a session, because blood pressure drops.
- Dehydration, from sweating, especially after exercise or over several rounds.
- Overheating, from staying in too long. Heat exhaustion can turn into heatstroke, which is an emergency.
- Burns from hot stones, stoves or metal jewellery.
- Slips on wet floors and steps.
- Cold water shock, if you follow the sauna with a plunge or open-water dip. See cold water shock.
Warning signs: when to get out
Leave the sauna, cool down and drink water if you feel:
- dizzy or light-headed,
- sick,
- a headache,
- a pounding or irregular heartbeat, or
- confused or unusually tired.
Call 999 if someone is confused, collapses, has a fit or doesn’t recover after 30 minutes of cooling down.
Pages in this section
- Who should avoid saunas, including heart conditions and medicines
- Saunas in pregnancy
- Alcohol and saunas
- Saunas, sperm and fertility
In this section
- Who should avoid saunas? Heart conditions, medicines and more
Who shouldn't use a sauna, who should check with a doctor first, and which medicines and health conditions make saunas riskier.
- Can you use a sauna when pregnant? UK advice and evidence
Saunas, steam rooms and hot tubs in pregnancy: what the NHS advises, what studies of heat and pregnancy show, and how to stay cool.
- Alcohol and saunas: why they don't mix
Why drinking alcohol before or during a sauna is risky, what Finnish data on sauna deaths shows, and how long to wait after drinking.
- Do saunas affect sperm and male fertility?
What happens to sperm count and quality with regular sauna use, whether the effect is reversible and what to do if you're trying for a baby.
Common questions
What are the side effects of a sauna?
The most common are feeling light-headed or faint on standing, headache, and dehydration. Overheating, heat exhaustion and, rarely, heatstroke can happen if you stay in too long, especially after drinking. Men who use saunas often may have a temporary drop in sperm count.
Can a sauna be bad for your heart?
For most people, saunas appear to be good for the heart. But people with unstable angina, a recent heart attack, severe aortic stenosis or uncontrolled blood pressure should avoid them, and anyone with a heart condition should check with their doctor first.
Can children use a sauna?
In Finland children often join their families in the sauna, usually for shorter times and on lower benches. Children overheat more easily, so keep sessions short, supervise them closely and follow the venue's age rules.
References
- Kenttämies A, Karkola K. Death in sauna. Journal of Forensic Sciences, 2008.pubmed.ncbi.nlm.nih.gov
- Hannuksela ML, Ellahham S. Benefits and risks of sauna bathing. American Journal of Medicine, 2001.pubmed.ncbi.nlm.nih.gov
- Kukkonen-Harjula K, Kauppinen K. Health effects and risks of sauna bathing. International Journal of Circumpolar Health, 2006.pubmed.ncbi.nlm.nih.gov
- Hussain J, Cohen M. Clinical effects of regular dry sauna bathing: a systematic review. Evidence-Based Complementary and Alternative Medicine, 2018.pubmed.ncbi.nlm.nih.gov
- NHS. Heat exhaustion and heatstroke.nhs.uk
First published 4 November 2026. Spotted an error? Tell us and we'll correct it. Read our editorial policy.