Hot baths may rival saunas for cardiovascular benefit – and cost far less. Research from the University of Oregon found bathing can lower blood pressure and support immune function, while a British Heart Foundation–funded trial at Manchester Metropolitan University is testing whether warm-water immersion eases peripheral artery disease symptoms.
At a time when the wellness industry is booming and sauna sessions can be costly, an evidence-backed alternative may sit behind most bathroom doors. Though showering has displaced bathing in many households, the majority of UK homes still have a bathtub.
How hot baths may improve circulation and heart health
- Immersion in hot water raises your core temperature, which drives blood from the organs toward the skin – a mechanism that appears to benefit circulation.
- University of Oregon research indicates bathing may lower blood pressure and boost immune function; other studies suggest benefits comparable to aerobic exercise and reduced blood sugar.
- With backing from the British Heart Foundation, Manchester Metropolitan University is running a trial of hot-water immersion as a treatment for peripheral artery disease (PAD) – a widespread circulatory condition that typically strikes the arteries of the lower legs and makes walking painful.
- Researchers themselves advise checking with your GP first, particularly if you have low blood pressure.
Why heat therapy is moving from the spa to the clinic
Peripheral artery disease usually affects the arteries of the lower legs, restricting blood flow and making walking painful. The Manchester Metropolitan team, supported by British Heart Foundation funding, is examining whether regular immersion in water heated to 40C – a few degrees warmer than hot tubs are typically set – can relieve PAD symptoms.
Stockport-based Ken Heywood, 75, took part in the eight-week heat-therapy trial after his PAD symptoms, first diagnosed when he was 38, worsened. He attended monitored hot-tub sessions three times a week. By the end, he said his blood pressure had improved and his walking had got better. He surpassed his goal of completing his daily dog walks without stopping at every bench and climbed to the top of a hill in his local park that would previously have terrified him.
After the study wrapped up, Heywood maintained a routine of three weekly baths at home, combined with physiotherapy and exercise, and says he is still seeing benefits. “It’s a lot easier than exercising on a treadmill,” he said.
The mechanism: what hot water does to your circulation
William Carey, one of the academics running the trial, explained the physiological mechanism: bathing in hot water improves blood circulation because core temperature rises, driving blood to the skin and away from the organs. For someone like Heywood, whose body does not send blood to his legs efficiently, that redistribution is particularly helpful – but Carey said it is likely good for most people’s cardiovascular health. He caveated this with a recommendation to consult your GP, especially if you have low blood pressure.
Other research has suggested a bath’s benefits could be comparable to aerobic exercise and that bathing may reduce blood sugar levels. The University of Oregon work found bathing can lower blood pressure and boost the immune system.
From the four humours to hospital hydrotherapy
The idea that baths heal is old. Humorism, the medical system practised from the fifth century BC to the 17th century AD, held that illness came from imbalances in four body fluids – blood, phlegm, yellow bile and black bile – each classed as hot, cold, dry or moist. Medical historian and retired GP Roger Rolls said that if a patient was judged to have an excess of a dry humour, bathing in hot water was considered a good way of rebalancing things; the theory was applied to conditions from cataracts to arthritis.
When microbes were discovered in the 17th century, humorism was debunked – but doctors kept finding bathing effective for certain aches, pains and skin diseases. Rolls conceded some of that may have been placebo effect, yet some was real. Even now, he noted, “quite a lot of hospitals have their own hydrotherapy department”, using immersion in water to help rehabilitate people with neuromuscular disorders.
The mental health dividend patients report
Bathing also offers a deliberate mental break. Grace Booth, who bathes four or five times a week, said: “As a busy working mum, I rarely have time to myself, and I really struggle with feeling I should always be doing something productive. My mind can run away with me, so baths are my enforced relaxation time.” After a bath, she feels rested and re-centred – and pointed out that we build calming bath and bedtime routines for children but forget to give ourselves the same wind-down.
Heywood reported the same dual benefit: lying there and just relaxing. He plans to continue hot baths alongside an increased exercise regimen, both of which appear to be reducing his pain.
| Setting | Water temperature | Frequency observed | Reported effects |
|---|---|---|---|
| Manchester Metropolitan trial (hot tub) | 40C | Three sessions weekly, eight weeks | Improved blood pressure and walking ability in a PAD patient |
| Home bathing (post-trial) | Hot bath | Three baths weekly | Ongoing positive results alongside physiotherapy |
| Typical hot tub | A few degrees cooler than 40C | – | – |
Who should see a doctor before hot bathing
- Low blood pressure: Carey specifically recommended consulting a GP before regular hot bathing if you have low blood pressure, since heat-driven redistribution of blood to the skin can lower it further.
- Established cardiovascular disease: the Manchester Metropolitan trial is still a research study; anyone with PAD or heart disease should discuss heat therapy with their clinical team before starting.
For now, the practical takeaway from the researchers is modest: three hot baths a week, a GP conversation first if your blood pressure runs low, and no expectation that a bathtub replaces a treadmill.
References
- University of Oregon research on bathing, blood pressure and immune function.
- Manchester Metropolitan University heat-therapy trial for peripheral artery disease, funded by the British Heart Foundation.
- Interviews with William Carey (Manchester Metropolitan University), Roger Rolls (medical historian and retired GP), Ken Heywood (trial participant) and Grace Booth.
