Hydrotherapy, Hot Tubs and Heart Health: What Is Known and Cautions

Urgent first

Chest pain, severe breathlessness, fainting, or feeling that something is seriously wrong in a hot bath, hot tub or sauna means getting out safely if you can and calling emergency services; in the United States that is 911. The NHS says to get help from NHS 111 in the UK if you have chest pain that comes and goes [1]. This page is information only. Never stop or change blood pressure medicine because of a bath, and do not use hot water instead of care you have been prescribed.

The short answer

Hot-water immersion lowers blood pressure for a period afterward in the small studies we read, and some researchers propose that regular heat exposure may help heart health. But the studies are few, small and short, and the long-term benefit is unproven. A 2026 review said heat therapy consistently induced transient reductions in blood pressure, but that long-term antihypertensive efficacy is unproven and safety margins in frail older adults and beta-blocker users remain insufficiently defined [2]. Evidence label: promising but limited for short-term blood pressure changes; insufficient evidence for preventing heart disease.

What the sources found

1. Does one hot soak lower blood pressure over 24 hours?

   Unclear

   In a randomized crossover study of 16 people with hypertension (all taking at least one blood pressure medicine), systolic pressure over the next 24 hours was 6 to 7 mm Hg lower after hot-water immersion than after no immersion [3]

   Very small; short term

2. Is heat itself needed?

   Unclear

   The same study found a similar drop after a thermoneutral immersion, so water immersion alone, not only heat, may matter [3]

   Very small

3. What do reviews say?

   Unclear

   A 2026 narrative review across saunas, hot springs, hot-water immersion and mudpack therapy found reductions of about 11 to 27 mm Hg in systolic pressure within 24 hours, but most studies lacked control groups and varied widely [2]

   Low; heterogeneous

4. Is it safe in older adults and people on beta-blockers?

   Unclear

   The review found serious acute adverse events were rare but few studies targeted adults 65 and over or reported their medicines and conditions [2]

   Insufficient

5. Does it prevent heart disease?

   Unclear

   Authors of a 2025 perspective propose hot-water immersion as an alternative to exercise for people unable to be active. It is an argument by proponents, not trial proof [4]

   Perspective article

6. How might it work?

   Unclear

   A 2021 review of mechanisms describes heat therapy, meaning chronic, repeated hot baths or saunas, as showing beneficial effects on cardiovascular health in a growing number of studies [5]

   Mechanism review; proposed, not proof of outcomes

What these results do and do not mean

A drop in blood pressure in the hours after a bath is a physiological change, not proof of fewer heart attacks or strokes. Participants could not be blind to the water, and the crossover study had 16 people. The temperatures studied (40 degrees C hot, 36.5 degrees C thermoneutral, for 20 or 40 minutes) describe that study only [3]. They are not advice, and tolerance varies. Because the same effect can cause dizziness or fainting when you stand up, see fainting, dizziness and low blood pressure after hot water.

Who needs to check with a clinician first

People with heart disease, arrhythmia, high or low blood pressure, older adults, and people taking blood pressure medicines, diuretics or beta-blockers should ask a clinician before using hot tubs, hot baths or saunas. The 2026 review specifically flags frail older adults and beta-blocker users as groups where safety is not well defined [2]. Our guides cover hydrotherapy with heart conditions and blood pressure problems, hydrotherapy and medicines, and heart attack, arrhythmia and sudden death risks with heat and cold. Alcohol with heat is dangerous: see alcohol, drugs and hydrotherapy.

Saunas, cold water and where they are covered

Sauna and cold-water evidence on heart outcomes is owned by our Specialty Topics pages: temperature exposure and cardiovascular conditions, sauna: evidence summary and cold-water immersion: evidence summary. We do not repeat them here.

What lowers blood pressure with better evidence

The NHS says high blood pressure can lead to heart attacks or strokes, and that lifestyle changes and blood pressure medicines can help you stay healthy [1]. It also says the only way to find out whether you have high blood pressure is to have it checked [1]. Warm-water exercise is a separate topic: see warm-water bathing, aquatic exercise and aquatic therapy.