Hot Flashes: Causes, Tests & Relief

What Are Hot Flashes?

A hot flash is a sudden feeling of intense heat, often with sweating and a flushed face, typically lasting a few minutes. They are most commonly linked to perimenopause and menopause but can have other causes.

Common Causes

• Perimenopause and menopause (most common cause)
• Hyperthyroidism (overactive thyroid)
• Certain medications
• Anxiety and stress
• Some medical treatments (e.g. hormone therapy for cancer)
• Rarely, an underlying endocrine disorder

Tests Your Doctor May Order

Tips for Relief

• Dress in layers and keep your environment cool
• Avoid common triggers: spicy food, caffeine, alcohol
• Practice slow, deep breathing when a flash starts
• Regular exercise can reduce frequency over time
• Discuss hormone therapy or non-hormonal medication options with your doctor if flashes are frequent or disruptive

Frequently Asked Questions

Managing hot flushes

Practical measures help many people: dressing in layers, keeping the bedroom cool, avoiding common triggers such as spicy food, caffeine and alcohol, and stopping smoking. Regular exercise and weight management are associated with fewer and less severe episodes.

Where symptoms significantly affect sleep or daily life, hormone replacement therapy is the most effective treatment for menopausal hot flushes and can be discussed with your doctor, who will weigh the benefits against your individual risks. Non-hormonal options, including certain antidepressants used at low dose, are available for those who cannot or prefer not to take HRT.

References

Sources cited on this page. PubMed links open the original abstract.

1. Freeman EW, Sherif K. Prevalence of hot flushes and night sweats around the world: a systematic review. Climacteric. 2007;10(3):197–214. PMID 17487647 · doi:10.1080/13697130601181486

The physiology of a hot flash – why it happens

Hot flashes (also called hot flushes) are caused by dysregulation of the hypothalamic thermostat – the part of the brain that controls body temperature. In menopause, falling oestrogen levels narrow the thermoneutral zone (the temperature range within which the body does not need to sweat or shiver). As a result, small rises in core body temperature – even within the normal range – trigger an exaggerated heat-dissipation response: peripheral vasodilation (flushing), sweating, and a feeling of intense heat radiating from the chest, neck, and face.

Hot flashes typically last 1–5 minutes and may be followed by chills as body temperature overshoots downward. They can occur many times per day and frequently disrupt sleep (night sweats). In some women, hot flashes persist for more than a decade after the last menstrual period – not just the 1–2 years commonly assumed.

Blood tests to exclude other causes

Although menopause is overwhelmingly the most common cause of hot flashes in women aged 45–58, blood tests are used when the diagnosis is uncertain or the clinical picture is atypical:

• FSH (follicle-stimulating hormone): Rises significantly in menopause as the pituitary gland tries to stimulate failing ovaries. A fasting FSH above 30 IU/L on two occasions, 6 weeks apart, in a woman over 45 with amenorrhoea for 12 months, confirms menopause. Note: FSH is not reliable in women taking hormonal contraception.
• Oestradiol: Falls significantly at menopause but fluctuates – a single result may be difficult to interpret. More useful as a baseline before starting HRT and for monitoring therapy adequacy.
• TSH: Hyperthyroidism causes sweating, heat intolerance, palpitations, and flushing – closely mimicking menopause. TSH should be checked to exclude thyroid overactivity before attributing hot flashes to menopause alone, particularly if weight loss or rapid heart rate is also present.
• Prolactin: A pituitary tumour (prolactinoma) can suppress oestrogen and cause hot flashes alongside amenorrhoea and galactorrhoea (milk production).
• Carcinoid and phaeochromocytoma markers (urine 5-HIAA, plasma metanephrines): Rare but important. Carcinoid tumours cause episodic flushing that is typically bright red and may be triggered by alcohol or food. Unlike menopause flushing, carcinoid flushing does not cause sweating and is often accompanied by diarrhoea and wheezing. A phaeochromocytoma (adrenal tumour) causes hypertensive episodes with sweating and palpitations.

Hormone replacement therapy – what current evidence shows

HRT is the most effective treatment for menopausal hot flashes, reducing frequency and severity by approximately 80–90% compared with placebo. Modern HRT regimens (especially transdermal oestrogen via patch or gel, combined with micronised progesterone) have a much safer profile than the combined oral preparations that drove the 2002 WHI study safety concerns. Current NICE guidance (NG23, updated 2024) recommends that HRT should be offered to women with menopausal symptoms after a discussion of individual benefits and risks – and that the benefits outweigh the risks for most women under 60 or within 10 years of menopause.