14 medications that make you sensitive to the heat

In this article:

• What is heat intolerance?
• Medications that cause heat intolerance
• Signs
• Treatment
• Prevention

In this article

• What is heat intolerance?
• Medications that cause heat intolerance
• Signs
• Treatment
• Prevention

Summer is in full swing—and there’s another heat wave slamming your area. You’re ready to hit the beach to cool off from the extreme heat. As long as you remember to reapply sunscreen and stay hydrated, you’re enjoying the hot temperatures safely…right? Not so fast! If you take any daily pills—prescription or over-the-counter—check with your pharmacist first. Certain medications that cause sun sensitivity and heat illness can ruin a day of fun in the sun, and have dangerous side effects as temperatures skyrocket. 

What is heat intolerance?

Also known as hypersensitivity to the heat, heat intolerance is more than just feeling uncomfortable when temperatures rise. It’s a condition that occurs when your body can’t regulate its temperature properly. 

As it gets hotter outside, the hypothalamus in your brain sends messages through your nerves that tell your skin to cool off by sweating. When the moisture evaporates off your skin, it decreases your core temperature. If something disrupts this process, your body is unable to cool down—and that can lead to unpleasant symptoms like nausea, dizziness, or even a heat-related illness.

RELATED: 6 heat-related illnesses you should watch out for this summer

Heat intolerance has many causes: certain health conditions, age, weight, and the medications that you take. 

14 medications that cause heat intolerance

There are several types of common medications that can increase your sensitivity to the heat:

1. Blood pressure medication
2. Antihistamines
3. Decongestants
4. Anticholinergics
5. Stimulants
6. Psychiatric medications
7. Steroids
8. Thyroid medications
9. Chemotherapy drugs
10. Muscle relaxants
11. Hormonal medications
12. Cholesterol-lowering medications
13. Antibiotics
14. Retinoids

Additionally, there are many combination drugs, so even if your medication doesn’t make this list, it’s always a good idea to check with a provider before heading out on a hot day.

1. Blood pressure medications

Certain prescription treatments for high blood pressure, also known as hypertension, can put you at higher risk of heat intolerance. This is especially true for two types of medications: thiazide diuretics and beta blockers.

Thiazide diuretics 

“Certain medications, called diuretics, force fluid out of our bodies through our kidneys to control high blood pressure and heart failure,” says David Cutler, MD, family medicine physician at Santa Monica Family Physicians in California. “These medications could cause dehydration, a potentially grave danger in hot weather.” Thiazide diuretics, such as chlorthalidone and Microzide (hydrochlorothiazide), are known to have this effect. Additionally, recent studies have found that hydrochlorothiazide, as well as combination drugs, may increase the risk of certain types of skin cancer.

Beta blockers

Beta blockers, such as Toprol XL (metoprolol) and Inderal (propranolol), can decrease blood flow to the skin, which can inhibit sweating. “It mainly has to do with how the blood flows to the skin,” says Dawn Shill, Pharm.D., a pharmacist for the Veterans Affairs Healthcare System in Anchorage, Alaska. “The blood vessels don’t dilate as they should to allow heat to escape with certain blood pressure medications. By constricting blood flow, the body can’t regulate temperature as much.”

Both effects make it harder for your body to cool off.

Other blood pressure medications

In addition to these medications, other medications used to lower blood pressure can cause severe sunburn and skin irritation. They include:

• Calcium channel blockers like amlodipine
• Angiotensin II receptor blockers (ARBs) like losartan
• ACE inhibitors like lisinopril

If you’re taking one of these medications and can’t avoid sun exposure, it is recommended that you use sunscreen with an SPF of over 30 and wear protective clothing.

2. Antihistamines

You take a daily dose of an antihistamine such as Benadryl (diphenhydramine) to manage your seasonal allergies. This over-the-counter treatment is very effective at stopping sniffling, sneezing, and itchy eyes. But did you know some of the same medications can prevent you from sweating? Combine that with the summer sun, and it can increase your chances of overheating. This effect is more common with first-generation antihistamines, like Benadryl. Second-generation antihistamines, such as Claritin, Zyrtec, and Allegra, are less likely to have this effect.

“Antihistamines produce an anticholinergic effect commonly referred to as a ‘drying’ effect,” explains Kristi Torres, Pharm.D., a member of the SingleCare Medical Review Board. “The same mechanism that allows antihistamines to slow mucus production is also responsible for your body producing less sweat. When your body is not able to sweat, it is difficult to regulate your internal temperature in the face of high external temperatures.” If this is a concern, ask your healthcare provider or pharmacist to help you select an appropriate antihistamine.

RELATED: Can I take antihistamines every day?

3. Decongestants

Getting sick is likely the last thing you’re thinking about in the summer. But, colds can strike year-round, even in warm weather. If you’re all stuffed up and reaching for the Sudafed (pseudoephedrine), you may need to postpone your pool day for some good old-fashioned rest and relaxation. 

“Decongestants work the same way as blood pressure medications, decreasing the blood flow to the skin,” Dr. Shill says. That can be dangerous on an already hot day.

4. Overactive bladder treatments

Anticholinergics block the action of involuntary muscle movements that can make you feel like you need the restroom when you don’t. That’s a positive when you’re dealing with incontinence or poor bladder control. Unfortunately, they have a side effect that can spell trouble in the summer. Medications like Ditropan (oxybutynin) or Detrol (tolterodine) can reduce sweating, which reduces your ability to cool off.

5. Stimulant medications for ADHD

Certain prescriptions that treat attention deficit hyperactivity disorder (ADHD) fall into a class of medications known as stimulants. This includes well-known medications such as Adderall (amphetamine/dextroamphetamine) and Ritalin (methylphenidate). These drugs raise your body temperature, increasing the risk of heat intolerance. 

On top of that, they physically constrict blood vessels and reduce blood flow to the skin. “In the heat, blood flow needs to be increased to the skin in order to cool the body down,” explains Anthony Puopolo, MD, board-certified physician and chief medical officer of LifeMD. Stimulant medications can prevent that reaction.

6. Psychiatric medications

Medications used to treat certain mental health conditions and Parkinson’s disease all have one thing in common: They affect the hypothalamus. Since this region of the brain is essential to cooling, it can inhibit your ability to reduce body temperature on hot days. These medications can also decrease your thirst reflex, increasing dehydration.

There are many different types of psychiatric prescriptions that can lead to heat intolerance or an exaggerated reaction to the sun:

• Antipsychotics such as Haldol (haloperidol) or Thorazine (chlorpromazine)
• Dopaminergics such as Sinemet (carbidopa/levodopa) 
• Tricyclic antidepressants such as Elavil (amitriptyline) and Pamelor (nortriptyline)
• Certain other antidepressants, such as Wellbutrin (bupropion) 

7. Steroids

Corticosteroids, like prednisone, can cause us to sweat more or change how blood circulates in our skin, dysregulating how our bodies control temperature. For people on long-term steroid treatment, this often means feeling extra sensitive to heat and a higher risk of heat-related issues.

8. Thyroid medications

If you’re taking medications for thyroid disorders, such as Synthroid (levothyroxine) for hypothyroidism, you might notice you’re more intolerant to heat. These medications can boost your metabolism and energy use, which sometimes leads to too much thyroid hormone in the body. The result? You experience excessive sweating and feel warmer than usual, even in places where you’d typically be comfortable.

9. Chemotherapy drugs

Some chemotherapy drugs, like Doxil (doxorubicin) or cyclophosphamide, can interfere with internal heat regulation. They may affect the hypothalamus, harm the cells that help with thermoregulation, and cause fevers and other reactions that make you more sensitive to heat. Patients going through chemotherapy often struggle with heat, especially during their treatment cycles.

10. Muscle relaxants

Muscle relaxants such as Amrix (cyclobenzaprine) and Fleqsuvy (baclofen) can lead to heat intolerance because they affect the central nervous system, which regulates temperature. These drugs might make it harder for your body to sweat or change how you perceive temperature, making you feel uncomfortable in warm conditions. 

11. Hormonal medications

Hormonal treatments, including estrogen replacement therapy and certain contraceptives, can influence how your body handles heat. Estrogen can affect blood flow and sweating, increasing heat sensitivity, especially when starting treatment. Women on hormone therapy may experience hot flashes and other symptoms that make them feel uncomfortably warm during physical activity or in hot environments.

12. Cholesterol-lowering medications

Statins, such as simvastatin, atorvastatin, pravastatin, and lovastatin,  are commonly prescribed to treat high cholesterol and lower the risk of heart attack. These medications can cause photosensitivity, resulting in an itchy, painful rash after sun exposure and increasing sunburn risk. 

If you take any of the above, talk to your healthcare provider or pharmacist before planning a picnic in the heat of the day.

13. Antibiotics

While they won’t make you sensitive to high temperatures, certain antibiotics can make you more sensitive to the sun and likely to burn. Examples include tetracyclines, sulfa antibiotics, and quinolones like ciprofloxacin or levofloxacin. If you are taking an antibiotic, check with your healthcare provider to see if you need to take any precautions regarding sun exposure.

14. Retinoids

Retinoids, including both prescription-strength retinoic acid and over-the-counter retinol, can increase your skin’s sensitivity to sunlight. They work by speeding up cell turnover, which can thin the outer layer of skin and reduce its natural protective barrier. As a result, skin becomes more prone to sunburn, irritation, and heat-related reactions. This heightened sensitivity is why it’s often recommended to apply retinoids at night and use broad-spectrum sunscreen daily.

What signs of heat intolerance should you watch for?

The first sign of heat intolerance is feeling hot and uncomfortable. In addition, you might experience symptoms such as:

• Headache
• Dizziness
• Cramps
• Nausea or vomiting
• Weakness
• Flushed skin

What to do if you experience heat intolerance

When these signs appear, take steps to go indoors and cool off as soon as possible. Remove excess clothing, drink cool water, and apply cool compresses to your body. 

If you remain in the heat, you could develop symptoms such as rapid breathing, decreased sweating, or altered mental state. “A person should seek medical care if they are experiencing the aforementioned symptoms,” Dr. Puopolo says. These symptoms can mean that your heat intolerance is progressing to a heat-related illness, such as heat stroke, which may be fatal when untreated.

How to prevent heat intolerance

Prevention is always the best treatment. If you are on any of the medications known to increase the risk of heat intolerance, take extra precautions before you head outdoors:

• Carry water with you and drink it regularly to stay hydrated.
• Wear a hat to keep excess sun off your body.
• Avoid spending prolonged periods outdoors during the heat of the day.
• Wear loose-fitting, lightweight clothing.
• Avoid exerting yourself too much when it’s hot.

When in doubt, drink a glass of water and sit down for a minute indoors. If your symptoms don’t subside quickly, it may be time to seek medical treatment. Be sure to keep a list of medications you are currently taking handy so that your treating healthcare provider can respond appropriately.