The short answer
Do not use a sauna if you have unstable angina, a recent heart attack, severe aortic stenosis, uncontrolled high blood pressure or poorly controlled heart failure, a fever or infection, or if you have been drinking alcohol. Speak to your GP or midwife first if you are pregnant, have low blood pressure or any heart condition, or take regular medication. For most healthy adults, sensible sauna use is well tolerated.
For most healthy adults, using a sauna sensibly is safe. Medical reviews describe sauna bathing as well tolerated, and very few serious problems happen in saunas. But heat puts real demands on your heart and circulation, so some people should avoid it or get advice first. This applies to portable saunas and sauna blankets as well as traditional saunas.
Do not use a sauna if
Medical reviews of sauna safety list these as reasons not to use one:
- Unstable angina (chest pain that comes on at rest or is getting worse)
- A recent heart attack
- Severe aortic stenosis (a narrowed heart valve)
- Uncontrolled high blood pressure
- Heart failure that is not well controlled
- A fever or an acute infection, such as flu
- After drinking alcohol
The same reviews say sauna use is generally safe for people with stable heart disease, such as stable angina or a heart attack long ago, if it is used sensibly. That is a decision to make with your doctor, not on your own.
Check with your GP first if
- you have any heart condition, even if it is stable
- you have low blood pressure, or feel dizzy when you stand up
- you have severe heart valve disease
- you are pregnant or trying to get pregnant
- you take medicines that affect blood pressure, heart rate, fluid balance or sweating
- you have epilepsy, diabetes with nerve damage, or a condition that affects how you sense heat
- you have broken or inflamed skin, or a skin condition that heat makes worse
Pregnancy
The UK Teratology Information Service, which advises on medicines and exposures in pregnancy, says there is no clear yes or no on saunas. Studies are limited and mixed. The main concern is that raising your core temperature to around 40°C in early pregnancy may increase the risk of some birth defects. Three studies of sauna use found no link, while findings for hot tubs are mixed.
In Finland, where most pregnant women use saunas, rates of problems are similar to countries where saunas are not common. Even so, if you are pregnant, speak to your midwife or GP before using any sauna, keep sessions short and cooler, and stop if you feel too hot.
Children and older people
Children overheat faster than adults. Most healthy children tolerate short, supervised sauna sessions, but portable saunas are designed for adults. Follow the manufacturer’s guidance and never leave a child alone in one.
Older people are more likely to feel dizzy when standing up after heat, and may be on medicines that affect blood pressure. Start with shorter, cooler sessions and stand up slowly.
Alcohol and medicines
Never combine alcohol and a sauna. Medical reviews link drinking during sauna use with low blood pressure, heart rhythm problems, falls and, rarely, sudden death. Wait until it has completely left your system.
Some medicines, such as those for blood pressure, heart conditions and some mental health conditions, change how your body handles heat. If you take regular medication, ask your GP or pharmacist whether sauna use is OK for you.
Side effects to watch for
Most side effects come from staying in too long or not drinking enough water:
- dehydration and intense thirst
- dizziness or light-headedness, especially when standing up
- headache
- feeling sick
- muscle cramps
These can be early signs of heat exhaustion. Get out, cool down and drink water. The NHS advises calling 999 if someone is still unwell after 30 minutes of cooling and fluids, or if they have a very high temperature, hot skin that is not sweating, a fast heartbeat or breathing, confusion, a seizure or loss of consciousness.
How to use a sauna more safely
- Start with 10 to 15 minutes and build up slowly.
- Drink water before and after each session.
- Never use a sauna after alcohol, or when you are ill.
- Stand up slowly afterwards and sit down if you feel light-headed.
- Plug portable saunas straight into a wall socket, not an extension lead.
- Get out straight away if you feel unwell.
Our step-by-step guide to using a portable sauna covers this in more detail.
Questions
Who should not use a sauna?
Doctors advise against sauna use for people with unstable angina, a recent heart attack, severe aortic stenosis, uncontrolled high blood pressure or heart failure that is not well controlled. Do not use one if you have a fever or an acute infection, or after drinking alcohol.
Can I use a sauna if I have high blood pressure?
If your blood pressure is well controlled, sauna use is generally considered safe, but check with your GP first. If it is not controlled, do not use a sauna until you have spoken to your doctor.
Is it safe to use a sauna when pregnant?
The UK Teratology Information Service says there is no clear yes or no, because studies are limited and mixed. Raising your core temperature to around 40°C is the main concern in early pregnancy. Speak to your midwife or GP before using a sauna while pregnant.
What are the side effects of using a sauna?
The most common are dehydration, dizziness or light-headedness (especially when standing up), headaches and feeling sick. These are usually signs you have stayed in too long or not drunk enough water.
Can children use a portable sauna?
Most healthy children tolerate short, cooler sauna sessions with an adult present, but children overheat more quickly. Portable saunas are designed for adults, so check the manufacturer’s guidance and keep children’s sessions short and supervised.
Sources
- Laukkanen, Laukkanen and Kunutsor (2018). Cardiovascular and other health benefits of sauna bathing: a review of the evidence. Mayo Clinic Proceedings
- Hannuksela and Ellahham (2001). Benefits and risks of sauna bathing. American Journal of Medicine
- UK Teratology Information Service: Saunas and hot tubs in pregnancy
- NHS: Heat exhaustion and heatstroke
This guide is general information, not medical advice. If you have a health condition, are pregnant or take regular medication, speak to your GP before using a sauna.