Why antidepressants increase heat risk
Blog article: Why antidepressants increase heat risk
Why your antidepressant could make summer more dangerous
A warning sign circulating online this summer about antidepressants and hot weather has been catching people's attention — and for good reason. The message is medically accurate, backed by the CDC, NHS guidance, and peer-reviewed research. If you or someone you care about takes an SSRI, SNRI, or similar medication, the heat is a risk you genuinely need to plan for.
The science: how antidepressants interfere with heat regulation
The hypothalamus — the brain region that controls body temperature - is directly affected by elevated serotonin levels. SSRIs and SNRIs alter how serotonin flows through the brain, which can disrupt the signals that trigger sweating, thirst, and heat dissipation. The result: your body's cooling system doesn't fire as reliably when it should.
SSRIs tend to cause excessive sweating - which increases fluid loss and dehydration risk. Tricyclic antidepressants (TCAs) work in the opposite direction, suppressing sweating altogether, which prevents the body from cooling itself through evaporation. Both outcomes are dangerous in a heatwave.
A 2022 review cited by Medical News Today found that SSRIs and TCAs can cause core body temperature to rise above 41°C (106°F). There is also evidence that some psychotropic drugs can dull a person's self-perception of how hot they are — making it harder to recognise when heat is becoming dangerous.
41°C - Max core temp risk
5 - Meds named in advisory
CDC - Confirmed by clinicians
Who is most at risk?
The risk is higher for older adults, those on multiple medications simultaneously, and anyone with underlying conditions like heart disease or kidney problems. People taking lithium alongside antidepressants face additional danger: dehydration from sweating concentrates lithium in the blood, which can tip into lithium toxicity - a potentially life-threatening situation requiring immediate medical attention.
What to do — and what not to do
Do this
- Drink water consistently throughout the day - don't wait until you feel thirsty
- Stay indoors or in shade during peak heat (11am–3pm)
- Tell your GP you are on antidepressants before summer or during a heatwave
- Know the signs of heat exhaustion: dizziness, nausea, heavy sweating, rapid pulse
Do not do this
- Do not stop taking your antidepressants abruptly - this causes serious withdrawal effects
- Do not assume you'll "feel it coming" - heat perception may be dulled
- Do not ignore symptoms expecting them to pass on their own in extreme heat
Sources and further reading
CDC — Heat and Medications: Guidance for CliniciansMedical News Today — Antidepressants and heat intolerance (2023)Rethink Mental Illness — How SSRIs affect body temperaturePMC / NCBI — Systematic review: medications and core temperature during heat stress (2024)Remedy Psychiatry — Antidepressants and heat complications
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