By: Daria Horbal, Pharm.D, RPh

Heat intolerances (hypersensitivity to heat) occur when your body is unable to cool itself through sweating. This may be caused by medications, certain health conditions, age, or weight. A person who is hypersensitive to heat may begin to feel nauseous, dizzy or develop a heat-related illness.

The following medications may cause heat intolerance:

  1. Blood pressure medications
  • Thiazide Diuretics, i.e., chlorthalidone and hydrochlorothiazide control high blood pressure by forcing fluid out through the kidneys which could result in dehydration in hot weather.
  • Beta Blockers, i.e., Lopressor (metoprolol) and Inderal (propranolol) may reduce blood flow which in turn can reduce sweating.
  1. Antihistamines

First generation antihistamines, i.e., Benadryl (diphenhydramine) slows mucus production to ease allergy symptoms but may also cause decreased sweat production.

  1. Decongestants

Decongestants, i.e., Sudafed (pseudoephedrine) decrease blood flow to the skin thereby restricting the release of body heat.

  1. Overactive Bladder Treatments

A side effect of medications for overactive bladders, i.e., Ditropan (oxybutynin) and Detrol (tolterodine), is sweat reduction which prevents cooling down in the heat.

  1. Stimulant Medications for ADHD

These stimulants, i.e., Adderall (amphetamine/dextroamphetamine) and Ritalin (methylphenidate) raise your body’s temperature and restrict blood flow to the skin, possibly causing heat intolerance.

  1. Psychiatric Medications
  • tricyclic antidepressants, i.e., Elavil (amitriptyline) and Aventyl (nortriptyline),
  • antipsychotics, i.e., Haldol (haloperidol) and Thorazine (chlorpromazine),
  • dopaminergics, i.e., Sinemet (carbidopa/levodopa)

These medications that treat certain mental health conditions affect the body’s cooling system and may cause dehydration by decreasing the thirst reflex.

The best advice for people with heat intolerance to medication is to be aware of it and take precautions. Common sense remedies such as keeping hydrated, avoiding the sun for long periods of time, wearing a hat and sunscreen and staying in cool and shaded areas would help.