On June 23, 2026, the UK Health Security Agency (UKHSA) issued a warning to UK residents about the ongoing heatwave, highlighting that certain medications, including common antidepressants, can increase the risk of heat-related complications. The agency advised people to take extra precautions as temperatures soar across the country.
Medications That Increase Heat Sensitivity
The UKHSA explained that medications commonly taken for chronic conditions, such as diuretics, beta-blockers, and drugs used to treat mental health issues—like antipsychotics and common antidepressants known as SSRIs—can alter the body's ability to cool itself or retain fluids. This makes individuals more susceptible to heat-related illnesses. The agency urged people to read guidance on how to stay cool and well during hot weather and to take extra care if they are on such medications.
SSRIs and Heat Intolerance
Rethink Mental Illness, a mental health charity, notes that selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) are types of antidepressants that can cause excessive sweating—a common side effect that affects how the body regulates temperature. Examples of SSRIs include citalopram, fluoxetine, sertraline, and paroxetine. SNRIs, which are similar, include duloxetine and venlafaxine.
Rethink confirms that antidepressants can increase the likelihood of heat exhaustion, dehydration, and, in severe cases, heat stroke. This risk is higher for individuals who are older, take multiple medications, or spend long periods in hot environments.
Broader Health Risks During Heatwaves
The UKHSA emphasized that hot weather does not only present a risk of heat-related illness but can also worsen existing health conditions. People with cardiovascular, respiratory, or kidney problems, or those on certain medications, may experience a worsening of their underlying illness during a heatwave. The agency explained that when the body tries to cool itself down, it puts additional strain on organs that may already be under pressure.
For example, people with heart disease may find it harder to maintain adequate blood flow, leading to chest pain or even heart failure. Those with chronic obstructive pulmonary disease (COPD) or asthma may struggle to breathe as hot air, pollution, and dehydration combine to inflame airways and reduce oxygen intake. Individuals with kidney disease or diabetes are at increased risk of acute kidney injury when dehydrated in hot weather, as the kidneys become less effective at regulating body fluids.
Advice for Those on Medication
The UKHSA advises people to understand how their medication may affect their body's response to heat. It recommends checking the guidance and speaking to a doctor or pharmacist if they have any concerns. The agency also encourages everyone to follow general heatwave advice: stay hydrated, keep cool, and check on vulnerable individuals. For more information on medication and hot weather, visit Rethink Mental Illness. If worried, always speak with a doctor.
