Hot Flashes: Causes and Triggers

Hot flashes are most commonly caused by a decrease in estrogen, which can result from the hormonal changes of natural menopause, surgical menopause, or chemotherapy-induced medical menopause. Some hormonal therapies, such as tamoxifen, may also trigger hot flashes. Hot flashes can be especially severe in menopausal women who are undergoing breast cancer treatments that further disrupt estrogen levels. 

Menopause — whether natural or induced by treatment — is the most common cause of hot flashes. During menopause, your estrogen level falls, and that directly affects the hypothalamus. The hypothalamus is sometimes referred to as the body’s “thermostat”: It’s the part of the brain responsible for controlling body temperature, along with appetite, sleep cycles, and sex hormones. The drop in estrogen — along with other hormonal effects that come with menopause that are not well understood — confuses the hypothalamus and makes it think your body is too hot.

Research suggests that how quickly your estrogen levels drop might be the biggest factor in how you experience hot flashes and to what degree. The neurotransmitter serotonin may also play a role, which may be why medicines that increase serotonin ease hot flashes.

The brain responds to the hypothalamus by sending out an alert to the heart, blood vessels, and nervous system, telling them to cool down. As your heart pumps faster, the blood vessels in your skin dilate to circulate more blood to radiate off the heat, and your sweat glands release sweat to cool you off even more.

This is the same system that keeps your body from overheating in the summer. But when the process is caused by a drop in estrogen instead of actual heat, your brain's confused response can make you very uncomfortable. It doesn’t help that hot flashes happen at unpredictable and often inconvenient times. Your body is working to cool itself down when it doesn’t need to, and you feel miserable as a result: soaking wet in the middle of the workday or waking up drenched in the middle of the night.

Breast cancer treatments that can cause hot flashes include:

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  chemotherapy

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  hormonal therapy

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  ovarian suppression

All these treatments work by lowering the body’s natural levels of circulating estrogens, putting you in a menopausal state. Hormonal therapies that lower estrogen levels or block the hormone’s effects commonly cause hot flashes: tamoxifen causes hot flashes in more than 50% of those who take it, including people who are post-menopausal and have already experienced hot flashes. 

The hot flashes usually increase over the first several months of treatment and then get better. If they don’t or they’re affecting your quality of life, talk to your doctor, who may be able to lower your dose or switch you to a different drug. 

Other prescription medications can cause hot flashes, including opioids, antidepressants, certain medicines for osteoporosis, and some steroids.

Several things can also trigger hot flashes, including your diet, lifestyle habits, and even the temperature around you. If you’re having hot flashes, it can help to try to pinpoint triggers so you can avoid them. You may want to keep a record of when a hot flash happens and what you were eating or drinking at the time, as well as how you were feeling, both mentally and physically. 

Stress can boost the fight-or-flight response, which increases circulation and blood flow to the skin and can trigger a hot flash. Many people report stress as being the number one trigger for hot flashes. There are many ways to manage stress, such as tai chi, meditation, yoga, and breathing techniques. Find something that works for you and that you can stick with — these tools are even more helpful when you do them regularly. 

Alcohol is another hot flash trigger. It contains chemicals that can cause your blood vessels to dilate, which can trigger a sensation of sudden heat and skin flushing. You may have experienced a version of this even before menopause. If hot flashes bother you while drinking, you may want to consider avoiding alcohol altogether.

It’s not news to anyone that smoking is related to serious health problems, including cancer, strokes, and heart disease, but it may also trigger and worsen your hot flashes. Nicotine can disrupt your hormonal balance by preventing androstenedione, a hormone, from converting to estrogen, which raises the levels of circulating testosterone. The result is a dip in estrogen levels, which causes hot flashes. 

Caffeine is a well-documented hot flash trigger. Drinking beverages high in caffeine, such as coffee or soda, may increase your heart rate and cause your blood vessels to dilate, triggering a hot flash. If you think your caffeine intake may be triggering your hot flashes, you may want to consider switching to a beverage with less caffeine, like decaf coffee or herbal tea.  

Hot food and drinks have both been linked to hot flashes. Sticking to room temperature or cool food and drinks can help, especially if you’re already feeling overheated.

Avoid spicy foods and drinks, as well, as these also can trigger hot flashes. 

Hot weather and warm indoor environments can also make hot flashes worse. Depending on your resources and where you live, there may not be a lot you can do about it. If you can turn on a fan or an air conditioner, do — or try opening a window. You can also go to public places with air-conditioning, such as your local library or the grocery store to get relief.

Just as you should avoid hot food, beverages, and weather if you’re having hot flashes, it’s best to avoid hot tubs, heated pools, hot showers, and saunas. These can all trigger or worsen a hot flash. Stick to cool showers and baths to find some relief.