Yes, certain medications can make you more likely to experience heat-related illness. While we can’t control the weather, we can prepare and help more people stay safe.
To understand how medications can affect our bodies when outside temperatures rise, let’s look at the body’s normal cooling process.
Our warm-blooded bodies are designed to maintain a fairly constant internal temperature. When the temperature in our environment rises, our bodies have a number of cooling mechanisms to prevent overheating, including:
✅ Stimulation of sweat glands
✅ Increased blood flow to the skin (vasodilation)
✅ Changes in hormones to lower metabolism
✅ Behavior changes to help cool ourselves
But like all bodily systems, the body’s cooling mechanisms don’t always work perfectly. Likewise, they’re prone to disruptions, including from medications. Read on to learn what medications to watch out for.
➡️ Antidepressants
Antidepressants work by changing levels of neurotransmitters (brain chemicals). Some of these changes can also change how your body responds to heat.
Serotonin is a brain chemical that affects mood. It can also raise your body temperature and cause sweating. Many antidepressants affect serotonin, including SSRIs (selective serotonin reuptake inhibitors) and SNRIs (selective norepinephrine reuptake inhibitors). Popular examples of each include:
✅ SSRIs: fluoxetine (Prozac), paroxetine (Paxil), and sertraline (Zoloft)
✅ SNRIs: duloxetine (Cymbalta), venlafaxine (Effexor XR)
Since serotonin can raise your body temperature, taking antidepressants that raise serotonin levels may make you more vulnerable to heat exhaustion. But antidepressants can also make you less heat-tolerant by blocking a chemical in the body called acetylcholine. This action decreases your body’s ability to cool itself. Many medications can cause “anticholinergic” effects, which we discuss further below.
➡️ Blood pressure medications
People with heart-related conditions are more prone to heat exhaustion. Taking blood pressure medications may also make you more susceptible. Common types and examples include:
✅ ACE inhibitors: lisinopril (Prinivil, Zestril), enalapril (Vasotec)
✅ ARBs: losartan (Cozaar), olmesartan (Benicar), valsartan (Diovan)
✅ Calcium channel blockers: diltiazem (Cardizem, Tiazac, Cartia XT), verapamil (Veralan)
✅ Diuretics: hydrochlorothiazide (HCTZ), chlorthalidone (Thalitone)
If you take one or more of these meds, you may be more likely to get dehydrated on hot days. In addition to causing fluid loss, they can lower your thirst sensation, so you might become dehydrated without even noticing. What’s more, dehydration can worsen some blood pressure medication side effects such as electrolyte imbalances and dizziness.
✅ Beta blockers
Beta blockers are another class of blood pressure medication that are also used for heart conditions. They work by slowing your heart rate. This may decrease your ability to stay cool by allowing less blood flow to your skin’s surface. As a result, more heat stays trapped inside your body since less is brought to your body’s surface where it can escape into the air.
➡️ Substances that cause fluid loss
Dehydration is one of the main ways heat exhaustion leads to symptoms like dizziness, fatigue, and nausea. Some substances that cause fluid loss include:
✅ Diuretics (water pills) like hydrochlorothiazide (Microzide) or furosemide (Lasix)
✅ Some diabetes medications: SGLT2 inhibitors like empagliflozin (Jardiance) and canagliflozin (Invokana)
✅ Laxatives like bisacodyl (Dulcolax) or senna (Senokot)
✅ Antibiotics (when they cause diarrhea)
✅ Alcohol
Diuretics cause your kidneys to remove more water and salt. SGLT2 inhibitors treat diabetes by helping more sugar leave your body as urine, but this process also makes you lose water. Any medication that causes you to have diarrhea or loose stools leads to fluid loss. Consuming drinks with alcohol also has a dehydrating effect.
➡️ Anticholinergic medications
Blocking acetylcholine can affect your body’s response to heat. Many medications block acetylcholine. Some examples of types of medications with notable anticholinergic effects include:
✅ Antipsychotics like risperidone (Risperdal) and quetiapine (Seroquel)
✅ Parkinson’s disease medications like benztropine
✅ Bladder control medications: oxybutynin (Ditropan XL) and solifenacin (Vesicare)
✅ Antihistamines (sedating types): diphenhydramine (Benadryl) and doxylamine (Unisom)
✅ Antidepressants: especially tricyclic antidepressants like amitriptyline and nortriptyline (Pamelor)
Medications with anticholinergic properties can decrease your body’s ability to adapt to the heat in two ways:
- Decreased sweating
- Decreased blood flow to the skin
Both effects make it harder for heat to escape from your body. If heat becomes trapped, your body may overheat. Older adults are particularly sensitive to this effect.
➡️ Stimulants
Stimulants rev up your metabolism, causing your internal temp to increase. Common stimulants include:
✅ Medications for ADHD (attention deficit hyperactivity disorder), including:
- Methylphenidate (Concerta, Ritalin)
- Amphetamine mixed salts (Adderall)
- Lisdexamfetamine (Vyvanse)
✅ Cold and allergy medications containing pseudoephedrine (a decongestant)
✅ Weight-loss medications containing phentermine
Stimulants can also make it harder for your body to cool down when your body gets too hot. A common stimulant side effect is vasoconstriction (narrowing of blood vessels), which is the opposite of your body’s vasodilation cooling response that increases blood flow to the skin.
➡️ Sedatives
While sedatives might not directly interrupt your body’s cooling system, they may make you less likely to take actions that keep you safe in the heat. Common sedatives include:
✅ Benzodiazepines such as alprazolam (Xanax) and clonazepam (Klonopin)
✅ Opioid medications such as oxycodone and hydrocodone / acetaminophen
✅ Sleep aids (any over-the-counter or prescription medications that help you feel sleepy)
✅ Alcohol
If you get overheated after taking a sedative, you might be less likely to get water to drink, turn a fan on, or change into something cooler. You might also oversleep, not noticing how hot your surroundings are, while your body temperature climbs higher.
➡️ Thyroid replacement medications
Medications like levothyroxine (Synthroid) for low thyroid (hypothyroidism) can affect your body’s internal thermostat. Just like the thyroid hormone in your body, levothyroxine increases your body’s core temperature. And because levothyroxine may also increase sweating or cause diarrhea, dehydration when spending time in the heat is another concern.
➡️ How to stay safe in the heat
Heat exhaustion can happen to anyone. Early signs include dizziness, irritability, and weakness. Some people also experience fast heartbeat, nausea, or vomiting. Consider these signs to take action to do whatever you can to get cooler quickly. Getting help is essential if your symptoms are severe. If you don’t have access to cold water or a place to cool down, get help right away even if your symptoms feel mild.
It’s a good idea to know if you or a loved one may be more heat sensitive so you can prepare and have backup plans when temperatures rise, especially in homes without air conditioning. People who live in low-income areas or places with high levels of air pollution are also more likely to experience negative outcomes from extreme heat.
Your clinician or pharmacist can tell you if a new or current medication might affect your body’s natural cool-down system. However, medications are just one factor that may increase your risk of heat exhaustion. Taking extra precautions in the heat is also important if you:
✅ Are a child, older adult, or pregnant person
✅ Have a disability
✅ Live without air conditioning
✅ Have heart disease
✅ Have diabetes
✅ Have lower kidney function
✅ Work or play sports outside
Heat-related illnesses are preventable with planning. Staying informed will help. In the U.S., Heat.gov has tips for staying safe during a heat wave and includes weather maps with forecasts to help you plan. If heat exhaustion progresses, it can lead to heat stroke. Though not technically a stroke (like a brain attack), a heat stroke is also a life-threatening emergency that requires immediate medical care.
➡️ Remember other sun and heat considerations
Take extra care to protect your medications from exposure to heat and sunlight and avoid storing them in the car. Use an insulated bag (without an ice pack) when needed to keep on-the-go critical medications like insulin or epinephrine within their manufacturer’s recommended temperature range.
Also, take extra care to protect your skin from sunlight if you take a medication that increases sun sensitivity. Your prescription bottle or package may have a warning sticker on it if it’s one of them. You can also find a list here on the FDA’s website: The Sun and Your Medicine.
Stay informed. Stay ready. And stay safe while taking your medications
Further reading:
Preventing Heat-Related Illness
Who Is Most At Risk To Extreme Heat?
Heat-Related Illnesses and First Aid
5 Steps to Prepare for Hot Days For People with Heart Disease
