Hot flushes are due to vasomotor instability and are usually related to the female menopause.
Hot flushes are thought to be related to changes in central nervous system neurotransmitters and peripheral vascular reactivity. There is still much that is not understood. The aetiology of hot flushes in menopause would seem to be related to low oestrogen levels as the ovaries fail and the effect on central thermoregulation.
They do not tend to occur in men, as there is not a similar rapid decline in hormones. However, treatment for prostate cancer that involves suppression of testosterone production can produce a picture similar to menopausal hot flushes in women and can be just as severe.
- Reported prevalence varies greatly between studies.
- Hot flushes and night sweats substantially increase in frequency and severity during the menopausal transition.
- These symptoms are experienced by around 80% of menopausal women.
- They are most common in the first year following the last menstruation.
- Frequent menopausal vasomotor symptoms, including hot flushes, persist in more than half of women for more than seven years.
- Hot flushes can also occur in younger women with premature ovarian insufficiency.
- Most women are thought to try to manage their symptoms without seeking professional advice.
- They tend to be more severe in women of low body weight, those who take little or no exercise and those who smoke cigarettes.
- There is variation in frequency and duration between different races. Japanese women seem to have a particularly low incidence of hot flushes. In the USA, women of Afro-Caribbean origin have been shown to have flushes which last for more years than those of white women.
- An abrupt or early menopause causes more severe symptoms. Thus, surgical oophorectomy or its equivalent induced with chemotherapy, radiation or drugs produces more pronounced symptoms than a natural menopause.
- Hot flushes may last between a few seconds and 10 minutes but an average is around 4 minutes. Frequency may be from every hour to a couple of times a week.
- Hot flushes commonly affect the face, head, neck and chest.
- There is a sensation of intense heat and a feeling that the face and whole body are flushing. It is often difficult to ignore and women having hot flushes often fling open windows when all around them are anything but warm. Flushing and sweating may not be apparent to the observer but the person affected tends to be very self-conscious of the affliction.
- Lack of concentration and poor memory are commonly associated with hot flushes.
- Sleep disturbance is common with night sweats.
- Features of depression are not unusual.
- Frequent flushes and disturbance of sleep may be a major contributor to the commonly observed adverse effect on mood.
- Hormone replacement therapy (HRT) improves fatigue, depression, headaches and libido in men as well as in women. See separate Menopause and its Management article for more information.
- Inappropriate vasodilatation leads to a slight drop in core temperature. Between attacks there is no abnormality to be found.
Other causes of flushing to consider:
- Carcinoma of the pancreas.
- Carcinoid tumours.
- Phaeochromocytoma (may be part of a multiple endocrine neoplasia syndrome).
- Brain tumours and spinal cord lesions (can lead to vasomotor instability).
- Panic disorder.
- Diabetes insipidus.
- Frey's syndrome (flushing when the affected person eats, sees, thinks about or talks about certain kinds of food which produce strong salivation; may occur as a complication of parotid gland surgery).
- Some food substances - eg, monosodium glutamate.
- Some drugs - for example:
- Calcium-channel blockers.
- Selective serotonin reuptake inhibitors (SSRIs).
- Selective (o)estrogen receptor modulators (SERMS) such as raloxifene and tamoxifen.
- Anti-androgens such as cyproterone, spironolactone, bicalutamide, 5-alpha-reductase inhibitors.
- There may be a history of menstruation becoming irregular or ceasing but not necessarily. There may have been surgery, radiotherapy or chemotherapy, involving removal or inactivation of the ovaries. Similar causes of sudden withdrawal of sex hormones in men produce a similar response.
- Laboratory tests are not required in the following otherwise healthy women aged over 45 years with menopausal symptoms:
- Perimenopause based on vasomotor symptoms and irregular periods.
- Menopause in women who have not had a period for at least 12 months and are not using hormonal contraception.
- Menopause based on symptoms in women without a uterus.
- Follicle-stimulating hormone (FSH) levels should be undertaken in younger women.
Hot flushes do not threaten life but they can have a very detrimental effect on the quality of life. They will subside with time but a sympathetic and positive approach is required.
The following lifestyle advice should be given:
- Take regular exercise:
- Exercise training has been shown to reduce the severity of physiological symptoms that occur during a postmenopausal hot flush.However, other studies have not demonstrated this benefit with exercise.
- Weight loss in overweight women may improve symptoms.
- Wear lighter-weight clothing and sleep in a cooler room.
- Avoid possible triggers, such as spicy foods, caffeine, smoking, stress and alcohol.
HRT is the most effective treatment to relieve the symptoms caused by the menopause completely. The necessary duration of treatment is very variable but is usually months or often years. See separate Hormone Replacement Therapy (including Risks and Benefits) article for details.
Alternative pharmacological treatments to HRT
Some women consider alternatives to HRT to combat climacteric symptoms. They may not want to take HRT or have contra-indications to taking it.
These may include:
- Selective serotonin reuptake inhibitors (SSRIs) - effective for vasomotor symptoms in some women but their effect is often short-acting.
- Venlafaxine - can also be effective in some women.
- Clonidine- probably does work, although evidence is limited; side-effects such as dry mouth and tiredness can be a problem.Clonidine works by widening the thermoneutral zone. A trial of 2-4 weeks is required.
- Medroxyprogesterone acetate - can be beneficial for some women..
- The anticonvulsant gabapentin - can also be effective.
- Acupuncture or relaxation techniques - there is little evidence to support the use either.[11, 12]
- Phyto-oestrogens - naturally occurring compounds found in plant sources and structurally related to estradiol. Foods such as soy beans, as well as nuts, wholegrain cereals and oilseeds, are the foods most rich in phyto-oestrogens. Phyto-oestrogens can also be taken in the form of tablets containing concentrated isoflavones, such as red clover. However, the efficacy of phytoestrogens has not been proven in randomised clinical trials.One meta-analysis has shown that the use of phyto-oestrogens is associated with a reduction in frequency of hot flushes and that their side-effects are similar to those with placebo.
- Botanical medicines - there is a wide array of botanical medicines (such as black cohosh, sage, ginkgo biloba) available to take as an alternative approach to HRT for menopause. However, data documenting efficacy and safety are limited. None of the available botanical products is as effective as hormone therapy in the management of vasomotor symptoms.
Many women choose to try these products, as they believe them to be safer and more 'natural' than prescribed medication. However, most herbal products available in the UK are not subject to the same regulatory requirements as licensed medications and, as such, are not subject to the same degree of standardisation. There may be variability between products or a lack of clarity as to what ingredients a particular product contains.
In addition, there is currently insufficient evidence to suggest that they are safe to be taken by women with oestrogen-dependent cancer - eg, breast cancer. There are no safety data available in relation to their risk of venous thromboembolism (VTE).
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