Why Do Hot Flushes Happen? Sudden, at Night, in the Face
Why menopausal hot flushes happen, how long they last, what makes them worse, and the hormonal and non-hormonal treatment options available.
Short answer: A hot flush is a faulty response of the brain's temperature-control centre to falling oestrogen. Around 70-80% of women in the menopause transition experience it, and it lasts several years on average. Apart from the menopause, an overactive thyroid gland, some medicines, anxiety and alcohol can cause a similar complaint. It can be eased with many approaches, from lifestyle measures to hormone therapy.
The treatment options for hot flushes, which approach suits whom and the risks of hormone therapy are covered in detail on the hot flushes in the menopause and treating the menopause pages.
Why Do Hot Flushes Happen?
The brain's temperature-control centre (the hypothalamus) keeps body temperature within a narrow "safe zone". When oestrogen falls, the oestrogen brake on certain nerve cells in this centre is lifted and the safe temperature zone narrows markedly. As a result, even a very small rise in body temperature is read by the brain as "overheating". To cool the body quickly, blood vessels in the skin suddenly widen (a sudden flush and wave of warmth in the face and upper chest), and sweating follows; as the sweat evaporates and the body loses heat rapidly, chills, shivering and sometimes a feeling of palpitations (a racing or pounding heartbeat) can accompany it.
What Does a Hot Flush Feel Like, and How Many Minutes Does It Last?
A single hot flush episode usually lasts 2 to 4 minutes. How often they happen varies greatly from person to person: some women have one or two a day, while in others they can recur almost every hour, day and night.
An episode usually starts with a sudden, intense feeling of heat in the upper chest and face and spreads quickly over the whole body. As it begins there may be palpitations, unease or a feeling of anxiety. Sweating follows; as the sweat evaporates and the body cools rapidly, chills and shivering may be felt.
Hot Flushes in the Face and Facial Redness
A hot flush in the face is caused by blood vessels in the skin suddenly widening to cool the body; it is felt as redness and a wave of warmth across the face, neck and chest. Apart from the menopause, alcohol, spicy food, hot drinks and anxiety can also trigger sudden facial redness.
Hot Flushes at Night and Night Sweats
Hot flushes that happen during sleep are called night sweats. Most night sweats wake you up; because sleep is frequently broken, tiredness, difficulty concentrating, mood swings and anxiety during the day can increase. Keeping the bedroom cool, using thin, layered bedding and avoiding alcohol and heavy meals before bed can help. If night sweats come with a fever or weight loss, other causes should be investigated.
The Difference Between a Hot Flush and a Fever
Although it feels like a fever, the body's core temperature does not actually rise during a hot flush; the problem is the narrowing of the brain's temperature setting. For this reason, body temperature measured during an episode is usually normal. With a true fever, as seen in conditions such as infection, the thermometer reading rises and other symptoms such as weakness, shivering and aches accompany it.
What Causes Hot Flushes Apart From the Menopause?
The menopause is the most common cause of hot flushes, but not the only one. If you are not of menopausal age, or if the complaint has different features, the following causes also come to mind:
- An overactive thyroid gland (hyperthyroidism): May come with intolerance of heat, sweating, palpitations and weight loss.
- Some medicines: Hormone-suppressing medicines used in breast cancer treatment, some antidepressants and some hormone treatments can cause hot flushes.
- Anxiety and panic attacks: Can cause a sudden feeling of heat, facial redness and palpitations.
- Alcohol, caffeine, hot and spicy food: Can trigger sudden flushes in the face.
- Pregnancy and the period after birth: Hormone fluctuations can cause hot flushes.
- Infections: Sweating can occur together with a true fever (a rise in body temperature).
When should you see a doctor? If night sweats come with a fever, unexplained weight loss, persistent weakness or palpitations, if they started outside the age of the menopause, or if they are affecting your quality of life, an examination is needed.
How Long Do They Last, and How Common Are They?
Around 70-80% of women in the menopause transition experience hot flushes; in about a third, the symptoms are severe enough to disrupt daily life and sleep. According to a long-running study, the average duration is 7.4 years, and they can continue for an average of 4.5 years after the final period. In women whose symptoms start before the menopause (in perimenopause), the total duration can be longer. Hot flushes are not limited to the first years of the menopause either: symptoms can continue in around 40% of women over 60 and in 8-9% of women in their seventies.
What Makes Them Worse?
- Weight and abdominal fat: Can increase the frequency and severity of hot flushes.
- Smoking: Speeds up the breakdown of oestrogen, both bringing the menopause earlier and paving the way for episodes.
- Caffeine, alcohol, hot and spicy food and very hot drinks: Can trigger an episode by stimulating the temperature centre.
- Stress and anxiety: High stress levels can make symptoms more frequent.
- Surgical menopause: When the ovaries are removed surgically, hormone levels drop suddenly rather than gradually, so hot flushes can be much more severe.
Lifestyle and Non-Hormonal Options
Dressing in layers, keeping your surroundings cool, stopping smoking, managing weight and limiting alcohol and caffeine can bring relief. Regular exercise and yoga support general health and sleep quality, but controlled studies have found that on their own they do not markedly reduce how often hot flushes occur. Cognitive behavioural therapy (a form of psychotherapy based on changing patterns of thought and behaviour) has the strongest scientific evidence among non-hormonal options; it can markedly improve the stress and sleep disturbance caused by hot flushes. Prescription non-hormonal medicines (certain groups of antidepressants, nerve-pain medicines and newer medicines that target the brain's temperature centre) may also be considered following a doctor's assessment.
When Does Hormone Therapy Come In?
Hormone therapy is regarded in medicine as the most effective option for relieving hot flushes and night sweats, and it can reduce symptoms substantially. Bioidentical (body-identical) hormones are chemically identical in structure to those the ovaries naturally produce; because they are usually applied through the skin (gel, spray, patch), they do not strain the liver and do not increase the risk of blood clots. Starting hormone therapy within the first 10 years of the menopause or before the age of 60 can, as well as relieving hot flushes, help protect bone and cardiovascular health. However, every hormone therapy is individual; suitability is determined by a doctor's assessment.
With every treatment decision, results may vary from person to person. Getting detailed advice from your doctor before hormone therapy is recommended.
Frequently Asked Questions
Are hot flushes equally severe in every woman?
No. They can differ greatly from person to person depending on factors such as weight, smoking, stress levels and the way the menopause began (natural or surgical).
Do hot flushes only occur in the first few years of the menopause?
Although they ease within a few years for most women, in some women they can last more than ten years; there are cases where they continue even at an older age.
How many minutes does a hot flush last?
A single episode usually lasts 2-4 minutes; it can recur several times a day or more often.
What causes a sudden feeling of heat in the body?
The most common cause is the fall in oestrogen during the menopause transition. An overactive thyroid gland, some medicines, anxiety, alcohol and pregnancy can also cause a similar feeling of heat.
Are hot flushes linked to heart health?
Research shows that in women with moderate to severe hot flushes, cardiovascular risk factors such as high blood pressure can be seen together more often. For this reason, checking blood pressure, blood fats and blood sugar is also important in women with marked symptoms.