Heat Intolerance: Why You Overheat Easily and What a Visit Can Check

What it involves

MedlinePlus defines heat intolerance as a feeling of being overheated when the temperature around you rises, often with heavy sweating. It says the problem usually comes on slowly and lasts a long time, but it can also appear quickly because of a serious illness.

Who this is for

• Adults who feel overheated or sweat heavily in temperatures other people find comfortable
• Patients who started a new medicine and noticed they now tolerate heat poorly
• People with a fast pulse, flushing or shakiness along with the overheated feeling
• Adults who have had heat exhaustion before and want to know why heat affects them so much

What to expect

• Questions about when it happens, whether exercise makes it worse and whether you feel dizzy, flushed or have a racing pulse
• A review of every prescription, over-the-counter medicine and supplement you take
• Blood tests that can include a blood count, a metabolic panel and thyroid tests
• A plan based on the findings, or a referral if the cause belongs with a specialist

What heat intolerance looks like in daily life

It is more than disliking summer. People describe needing the air conditioning colder than everyone else in the house, sweating heavily during ordinary chores, or feeling wiped out after short stretches outdoors. MedlinePlus says a provider will ask when the symptoms happen, whether they are worse with exercise, and whether you have vision changes, dizziness or fainting, flushing, numbness or weakness, or a fast heartbeat. Noting those details for a week before the visit, along with the room or outdoor temperature, gives the provider something specific to work with.

Medicines that can make heat harder to handle

MedlinePlus lists several kinds of medicine that may lower heat tolerance: antihistamines, stimulants including some appetite suppressants, antibiotics, antidepressants, antipsychotics, blood pressure medicines, statins, decongestants, diabetes medicines, overactive bladder medicines, anti-inflammatory pain relievers and Parkinson disease medicines. It stresses that not every medicine affects every person the same way. A new symptom that began soon after a new prescription is a useful clue, so bring the full list. Please do not stop a prescription on your own, because stopping some of them suddenly causes its own problems.

Health conditions linked to feeling overheated

The MedlinePlus encyclopedia names cystic fibrosis, diabetes, cardiovascular disease, Graves disease, mental health conditions, multiple sclerosis, obesity and too much thyroid hormone among the conditions that can reduce heat tolerance, either from the condition itself or from the medicine used to treat it. Thyroid causes are why a visit usually includes blood work. The thyroid care page explains how thyroid problems are followed, and the guide to thyroid blood tests describes what the numbers mean.

Other things that raise the risk

MedlinePlus also lists alcohol use, a bacterial or viral infection, a past episode of heat exhaustion or heat stroke, poor physical fitness, menopause and pregnancy as factors that can make heat harder to tolerate. It adds that young children and older adults adjust to temperature extremes less well, and that older adults are more likely to take medicine that adds to the problem. Because the list is so wide, a provider tends to sort through it in order rather than guess, starting with what changed most recently in your health or medicines.

Staying safe in Florida heat while you find the cause

For prevention, MedlinePlus suggests drinking plenty of fluids, keeping indoor temperatures comfortable and limiting time outdoors in hot, humid weather. The CDC information summarized on its heat illness page notes that when it is very humid, sweating alone is not enough to cool you off. That is a fair description of a Palm Beach County summer afternoon. Read the heat exhaustion and heat stroke guide so you know the warning signs, and plan outdoor work or exercise for cooler hours.

When it is an emergency

MedlinePlus describes heat stroke as life threatening, with body temperature that can pass 106 degrees Fahrenheit within minutes. Its listed signs include dry skin, a rapid strong pulse, dizziness, nausea and confusion, and it says to get medical help right away. Heat exhaustion can bring heavy sweating, rapid breathing and a fast, weak pulse, and untreated it can turn into heat stroke. These are not reasons to wait for an appointment. Call 911 and move the person somewhere cooler while you wait.

Sources

• MedlinePlus: Heat intolerance (medical encyclopedia)
• MedlinePlus: Heat Illness (health topic)