Night sweats: when to see a doctor

See a GP if night sweats come regularly and wake you up or worry you, if they come with a high temperature, a cough or diarrhoea, or if you are losing weight for no reason. Those are the three signs on the NHS night sweats page. Without them, sweats in your forties and fifties are most often hot flashes from perimenopause or menopause, and you can raise them at your next routine appointment.

The checker below asks about those signs and a few more from the UK blood cancer charities, then tells you which of three answers fits. It sorts what you tick against published guidance. It cannot examine you, so treat the answer as a guide to how soon to book, never as a diagnosis.

How the checker decides

There is no score. Each answer either matches a sign a health body says is worth a GP visit or it does not, and the result is the most urgent band any of your answers reaches.

• Get help now if you feel suddenly very unwell. Blood Cancer UK says to get medical help straight away in that case: 999 or A&E in the UK, 911 or an emergency department in the US.
• See your GP soon for any of the NHS signs: regular sweats that wake or worry you, a high temperature or feeling hot, cold or shivery, a cough, diarrhoea, or weight loss for no reason. It also covers two signs from the blood cancer charities. Lymphoma Action wants a GP to see any lump in the neck, armpit or groin that has not gone away after 2 to 3 weeks. Blood Cancer UK says the same of tiredness, or any symptom, that you cannot explain or that goes on for a long time.
• Talk to your GP or pharmacist soon if the sweats began after you started a new medicine or changed a dose. The NHS names some antidepressants, steroids and painkillers as causes.
• Mention it at your next appointment when none of the above applies.

In the US, "your GP" means your primary care doctor. The guidance is British because the NHS publishes the plainest list of when night sweats need checking, while American sources such as ACOG describe night sweats as hot flashes during sleep and give no separate list of warning signs.

Are night sweats a sign of cancer?

Sometimes, but rarely on their own. Drenching night sweats are one of three "B symptoms" of lymphoma, a blood cancer. The other two are a fever of 38°C (100.4°F) or higher and losing a tenth or more of your weight over six months without trying, according to Blood Cancer UK. Doctors use them to judge how far a lymphoma has developed, and Lymphoma Action says they are most common in Hodgkin lymphoma and fast-growing non-Hodgkin lymphoma.

The same charity pages are careful to add that most people with these symptoms do not have lymphoma. Their own rule is short: see a GP about any symptom you cannot explain, that goes on for a long time or that is unusual for you. A swollen gland in the neck, armpit or groin, usually painless, is the most common sign of lymphoma, which is why the checker asks about lumps separately. If your GP suspects something, Blood Cancer UK says the first step is usually a simple blood test.

Set against that, the NHS puts menopause hot flushes first on its list of common causes, ahead of anxiety, medicines, low blood sugar, alcohol and hyperhidrosis. Soaked sheets with daytime flushes and nothing else on the warning list point that way.

Night sweats after a new medicine

If the sweats started within a few weeks of a new prescription or a dose change, write down the date you started and the name of the medicine before you call. Keep taking it until you have spoken to a GP or pharmacist. The NHS says a GP who thinks a medicine is behind the sweats may prescribe a different one, which is a decision to make with them. If you take insulin or tablets for diabetes, mention that too, since low blood sugar at night is another cause on the NHS list.

A worked example

Imagine a reader aged 49. She wakes soaked about twice a week, the sweats wake her, and she has hot flashes by day as well. She has no fever, no cough, no weight loss and no lump, and she has not changed any medicine.

She has one warning sign: regular sweats that wake her. Her answer is "See your GP soon", with that one reason listed. Because she also has daytime flashes, the result tells her to mention them at the appointment, since a GP will ask about that pattern when deciding whether menopause is the likely cause. Had she ticked "now and then" instead of "regularly", her answer would have been to mention it at her next appointment.

What to bring to the appointment

A GP will want to know how often the sweats happen, what else you have noticed, and when they started. Two weeks of notes answer all three better than memory. Our printable night diary gives each night one line, with every night sweat graded mild, moderate or severe and the times you woke up. If you would rather keep the record on your phone, Her Good Days is a free app that logs night sweats with the time and severity next to your sleep and medicines, and can show the weeks before and after a day you pick, such as starting a new medicine. It turns the dates you choose into a PDF report for your doctor, marked as reported by you. The app store listings are coming soon.

Weigh yourself once now and write it down. If weight loss is the question, a number with a date is worth more to your GP than a looser waistband.

My take

I'd judge night sweats by what comes with them, far more than by how wet the sheets get. A fever, weight you are losing without trying or a lump that does not go away is the reason to book. I'd leave the late-night reading about cancer alone until a GP has checked those. If the answer is "see your GP soon", book it this week and do not wait to see whether the sweats settle. If it is "next appointment", I'd spend the time before it on the cheap fixes in our bedroom checklist and on a fortnight of the diary, so the appointment starts with facts. Come back to the checker if anything new appears, a fever or weight loss above all.

For causes and what helps at night, our night sweats section gathers everything on the subject, and menopause sleep problems covers the other reasons midlife nights go wrong.