Many pages online claim an infrared sauna can reduce swelling. The honest answer is more careful: warmth can feel good on stiff, puffy-feeling legs after a long day, but a sauna is not a treatment for swelling, and for some kinds of swelling heat is the wrong thing. This guide explains what heat does, who should avoid it, and how to think about it. It is not medical advice.
Quick Answer
An infrared sauna warms your body and raises your heart rate a little, and many people find that relaxing. There is no strong evidence that sessions reduce swelling. The NHS advises avoiding heat for the first couple of days after a sprain or strain, and says the heat from saunas and steam rooms may increase swelling in lymphoedema. If swelling is new, painful, one-sided or doesn't go away, see a doctor before using a sauna.
Sauna and Swelling at a Glance
| Type of swelling | Sauna? | Why |
|---|---|---|
| New sprain, strain or bruise (first 2 to 3 days) | Skip it | The NHS advises PRICE (protect, rest, ice, compress, elevate) and avoiding heat such as hot baths and heat packs for the first couple of days |
| Lymphoedema, or at risk after cancer treatment | Skip it unless your care team says otherwise | The NHS lists heat from saunas, steam rooms and sun beds as something that may increase the swelling |
| Swelling with a heart, kidney or liver condition | Ask your doctor first | Swelling can be a sign the condition needs attention, and heat adds strain on the heart |
| Red, hot or painful swelling, or swelling in one leg only | Skip it and get checked | Could be an infection or a blood clot |
| Mild, puffy ankles after a long day of sitting or standing | Not a fix | A short, comfortable session is unlikely to hurt if you're otherwise healthy, but it won't treat the cause; moving and raising your legs are the usual first steps |
What Heat Does to Your Body
When you sit in a heated cabin, the blood vessels near your skin widen, your heart beats a little faster and you sweat. These are normal, temporary responses to heat, and they fade after you cool down. For how a home infrared sauna heats you compared with a traditional sauna, see infrared vs traditional sauna.
What Is Known and What Is Not
Comfort: gentle heat makes many people feel looser and more relaxed for a while. That is a comfort effect, not a treatment.
Circulation: heat widens blood vessels while you are in it. Our circulation guide covers what small studies did and did not show.
Lymphatic system: there is no proof that a sauna "drains" the lymphatic system. Read what heat can and can't do for lymphatic health, including why lymphedema is a reason to check with a doctor first.
Detox: sweat is mostly water and electrolytes; it does not flush out fluid or waste in any meaningful way.
Common Causes of Swelling
According to the NHS, swelling in the ankles, feet and legs (oedema) is usually caused by sitting or standing in one position too long, too much salty food, being overweight, pregnancy, some medicines (including some blood pressure medicines, contraceptive pills, hormone therapy, antidepressants and steroids), varicose veins or thyroid problems. It can also come from an injury, an insect bite, an infection, a blood clot, or kidney, liver or heart problems. None of these is treated by a sauna, which is why the cause matters more than the heat.
When Heat Can Make Swelling Worse
Heat is not recommended on a fresh injury such as a recent sprain, because warmth increases blood flow to the area. Swelling can also be a sign of something that needs medical attention. Skip the sauna and get medical advice if:
swelling is in one ankle, foot or leg and you don't know why
the swelling is severe, painful, starts suddenly or keeps getting worse
the area is red or feels hot to the touch, or you have a high temperature or feel shivery
you also have swelling in your face or tummy
you have diabetes and your feet, ankles or legs are swollen
you have a heart, kidney or liver condition, or a diagnosis such as lymphedema
swelling has not improved after a few days
Call emergency services if swelling comes with shortness of breath, chest pain or tightness, coughing up blood, a racing heartbeat, or feeling faint or confused. These can be signs of a blood clot in the lungs.
Who Should Check With a Doctor First
Anyone who is pregnant, has a heart or circulation condition, has a fever or open wound, or takes medication that affects heat tolerance should ask a doctor before using any sauna. Our session time and safety guide covers how long to stay in and how to cool down.
If You Use a Sauna and Your Doctor Says It Is Fine
Start short: 10-15 minutes at the lower end of the temperature range.
Hydrate before and after, and avoid alcohol.
Cool down gradually and sit or lie down if you feel lightheaded.
Stop if you feel dizzy, unwell or notice swelling getting worse.
Light movement afterwards is a common way to wind down. For workout timing see sauna before or after a workout, and for joint stiffness see infrared sauna and joint pain.
The Bottom Line
Enjoy a sauna for what it reliably gives: warmth and a relaxing routine (see our infrared sauna benefits guide for what the research does and does not show). Do not use it to treat swelling, and get medical advice for swelling you are worried about.
Sources (checked November 2026): NHS pages on oedema, sprains and strains and preventing lymphoedema.
