Safety Guide
Saunas and cold plunges are remarkable tools, but they carry real risk. Read this before starting, and check in with a doctor first if any of the conditions below apply to you. Saavu's in-app safety features (heart-rate ceiling, hydration nudge, voice cues) are aids. You are still in charge of your own body.
Talk to a doctor first if you
- Have any history of cardiovascular disease, arrhythmia, or hypertension
- Are pregnant, may be pregnant, or are recently post-partum
- Are recently post-surgery or have an unhealed wound
- Take medications that affect blood pressure, hydration, or thermoregulation
- Have diabetes, especially with autonomic neuropathy
- Have Raynaud's, cold urticaria, or peripheral vascular disease (for cold plunge)
- Have severe respiratory disease
- Have a history of seizures triggered by heat or cold
Sauna safety
Heat dose, not heat shock
- Start with 8–10 minutes. Build over weeks, not days.
- Most modern sauna research (Finnish and Søberg's protocols) uses 80–100°C ambient. Hotter is not better.
- Step out the moment you feel light-headed, nauseous, or dizzy. Sit upright after stepping out. Do not stand quickly.
Hydration
- Drink water before, between rounds, and after. Plain water is fine for most sessions under 30 minutes; longer or repeated sessions benefit from electrolyte replacement.
- Skip the session if you arrive already dehydrated.
- Saavu's hydration nudge fires at the end of every session if you have enabled it. You can also enable it manually in Settings → Notifications.
Alcohol & drugs
- Never use sauna while intoxicated, recently intoxicated, or hungover.
- Stimulants (caffeine in excess, sympathomimetics, recreational stimulants) raise cardiac demand significantly when combined with heat. Avoid them on session days.
Heart-rate ceiling
Saavu watches your heart rate during sessions and shows a non-blocking warning if you exceed your personal ceiling for three consecutive samples. The default ceiling is the standard age-predicted maximum (220 − age) scaled to 85%, which approximates the upper end of safe aerobic effort for most healthy adults. You can lower this ceiling in Settings → Health if your doctor has set a more conservative limit. The ceiling is an aid, not a guarantee. Heed your own body first.
Cold plunge safety
- Never plunge alone in deep water. Cold-shock can cause involuntary gasping; that gasp underwater drowns people.
- Start with face immersion or feet-only for 30 seconds. Build up over weeks.
- Get out the moment you feel sharp peripheral pain, numbness that worsens, chest pain, or arrhythmia. Cold-induced after-drop can continue for 20 minutes after exit. Warm up gradually with movement and a light layer, not a hot shower.
- 2–5 minutes total per week at 4–11°C is the dose most cold-exposure research uses. More is not necessarily better.
- Do not combine cold plunge with breath-holding underwater. Hyperventilation before submersion has caused shallow-water blackout deaths.
Contrast protocol notes
The sauna-then-cold pattern is physiologically demanding. The rapid swing from peripheral vasodilation (in the heat) to vasoconstriction (in the cold) raises cardiac load. If you are new to contrast, finish on heat or rest for the first month. Always rest until your breathing settles before re-entering the sauna.
Pregnancy
Available evidence suggests brief sauna use (≤15 min, below 70°C) during pregnancy is unlikely to harm, but we strongly recommend consulting an obstetrician before any heat exposure during pregnancy. Cold plunge during pregnancy has limited safety data; default to avoiding it unless your doctor advises otherwise.
Children & adolescents
Children's thermoregulation is less efficient than adults'. Saavu is not for users under 16. Adolescents (16–18) should use saunas only with adult supervision and never alone in cold water.
When to seek medical help
Stop and get help immediately if during or after a session you experience:
- Chest pain, jaw pain radiating from the chest, or sudden arm pain
- Severe shortness of breath, especially when lying down
- Loss of consciousness, even briefly
- Sudden weakness or numbness on one side, slurred speech, or vision change
- Palpitations that don't settle within a few minutes of rest
- A rapid heart rate that stays above 130 bpm at full rest 10 minutes after leaving the sauna
- Nausea that persists with confusion or extreme fatigue (possible heatstroke)
Reporting concerns
If you encounter a venue listed on Saavu that you believe is unsafe or non-compliant with local regulations, email hello@saavu.app. We will investigate and unlist if substantiated.