When sauna is not appropriate, when to be cautious, and how to use it safely. Honest, no marketing spin, because this matters more than the upsides.
The list
Within 3 months of a myocardial infarction, with unstable angina, or with uncontrolled arrhythmias, sauna is not appropriate. Once cardiac rehabilitation has progressed and a cardiologist has cleared moderate exercise, sauna is typically reintroduced, and the long-term mortality data overwhelmingly favours its use.
The peripheral vasodilation caused by sauna can drop coronary perfusion pressure dangerously in severe aortic stenosis. Avoid until specialist sign-off.
First trimester, avoid. Maternal core temperature above 39°C in the first 8 weeks is associated with an elevated risk of neural-tube defects. Second and third trimester, consult your midwife or obstetrician; in much of Finland, late-pregnancy sauna at gentler temperatures (60–70°C, shorter sessions) is normal and considered safe, but UK practice errs cautious.
Combining sauna with alcohol significantly increases the risk of dehydration, heat stroke, syncope and fatal arrhythmias. Finnish autopsy data has historically linked alcohol consumption to the majority of sauna-related sudden deaths. Wait several hours after drinking; never sauna intoxicated.
If you are running a fever or fighting an active infection, heat exposure compounds rather than helps. Wait until you are symptom-free for 24–48 hours.
Stable, treated hypertension and stable coronary disease are not contraindications, the Laukkanen data covers exactly this population. Speak with your GP, start at lower temperatures and shorter durations, and progress slowly. The mortality data for this group is unusually favourable.
Generally safe, but heat can cause hypoglycaemia, particularly with insulin. Check glucose before and after, especially in the first few sessions. Members on SGLT2 inhibitors should be especially attentive to hydration.
Heat can transiently worsen MS symptoms (Uhthoff phenomenon). The effect is reversible on cooling. Many MS members use cooler infrared cabins (50–55°C) without issue and gain benefit, discuss with your neurologist.
Beta-blockers, calcium channel blockers, ACE inhibitors and diuretics all modify your cardiovascular response to heat, usually you'll feel hotter or drop blood pressure faster than expected. Antihistamines, anticholinergics and some psychiatric medications can impair sweating. Stimulant medications can raise heat-stroke risk. None are absolute contraindications but all are reasons to start cautious and inform our team.
Children thermoregulate less efficiently than adults. Finnish practice is to introduce sauna gradually after age 7, at lower temperatures, with short sessions. We do not offer sauna for under-16s at R1SE.
Wait for your surgical team's clearance. Healing incisions are at risk in moist heat. Once wounds are fully closed (typically 4–8 weeks), gentle infrared sauna can support tissue recovery.
Modern pacemakers and ICDs are generally compatible with sauna use, but the device manual is the source of truth. Some older models specify upper-temperature limits.
Side effects
Easily preventable, 500 ml before, 500 ml after, plus electrolytes. Watch for headache, dizziness, dark urine.
Heat-induced vasodilation can drop blood pressure briefly. Sit before standing; rise slowly from the bench.
Rare but possible heat urticaria. Stop if hives appear and consult a GP before resuming.
Rare in supervised sauna environments. Signs: cessation of sweating, confusion, very high body temperature, headache, vomiting. Cool immediately and seek help.
If you have a condition we haven't covered here, the team at R1SE Kelham will always pause to discuss before a session.
Continue Reading
Every sauna page on the R1SE knowledge library.
ReadCardiovascular, longevity, neuroprotection, immune, every claim cited.
ReadFinnish, infrared, steam, smoke, hybrid, how each works.
Read2,000 years from Finnish löyly to modern recovery rooms.
ReadBeginner to advanced protocols, frequency, timing.
ReadBryan Johnson, Huberman, Rhonda Patrick, Hugh Jackman.
ReadKnowledge is one thing, the body learns by doing. Book a Fire & Ice session, an infrared sauna, or our 8-person Finnish barrel sauna at the Kelham Urban Spa.