Warmth: Feeling Hot Inside or a Warm Area of Skin

Sudden feeling of warmth inside the body

A wave of heat that spreads through the chest, neck and face is caused by blood vessels in the skin widening (vasodilation) as the body tries to release heat.

Hot flashes

The most common cause in women aged about 45 to 55. A hot flash is a sudden feeling of intense heat in the upper body and face, often with flushing, sweating and a rapid heartbeat, lasting 1 to 5 minutes, followed by chills. It is caused by changes in the brain's temperature control as estrogen falls in perimenopause and menopause. Hot flashes also occur in men on hormone therapy for prostate cancer and in women taking tamoxifen.

Fever

A rising temperature can feel like warmth or chills. Measure it. Over 38 °C (100.4 °F) is a fever, usually from infection.

Anxiety and panic

Adrenaline from anxiety or panic causes sudden warmth, flushing, sweating, a pounding heart and fast breathing.

Food, drink and medicines

• alcohol, especially in people with the ALDH2 gene variant common in East Asian ancestry
• spicy food and hot drinks
• niacin (vitamin B3), calcium channel blockers, nitroglycerin, sildenafil, opioids and steroids
• some antidepressants that cause sweating

Overactive thyroid

Hyperthyroidism speeds up metabolism, causing a constant feeling of warmth, heat intolerance, sweating, weight loss, tremor and palpitations.

Less common causes

• Carcinoid syndrome: episodes of flushing with diarrhea and wheezing.
• Low blood sugar: warmth and sweating with shakiness.
• Infections such as tuberculosis and some lymphomas: warmth and night sweats with weight loss.
• Pregnancy: higher metabolism and blood volume.

A warm area of skin

When one spot feels warm, the most common reason is inflammation, where extra blood flows to an injured or infected area. Compare with the same area on the other side using the back of your hand.

A warm, swollen joint with fever may be a joint infection and needs urgent care.

Feeling hot but no fever

If you feel warm but your thermometer reads normal, common causes are hot flashes, anxiety, a warm environment, exercise, recent meals or drinks, medicines and an overactive thyroid. Track when the warmth happens, how long it lasts, and what comes with it, then share the record with your doctor.

How doctors find the cause

Your doctor will ask when the warmth happens, whether it is all over or in one area, and about menstrual changes, medicines, alcohol, weight change, palpitations and other symptoms. They will measure your temperature and examine any warm area. Possible tests:

• thyroid function blood test
• FSH and estradiol in some women with irregular periods (menopause is usually diagnosed from symptoms)
• blood count and inflammation markers for infection
• D-dimer and leg ultrasound for a suspected blood clot
• joint fluid test for gout or infection
• urine tests for carcinoid syndrome when flushing is unexplained

What helps

• Hot flashes: dress in layers, keep the bedroom cool, use a fan, limit alcohol, caffeine and spicy food, and stop smoking. Hormone therapy is the most effective treatment for many women. Non-hormonal options include certain antidepressants, gabapentin and fezolinetant.
• Anxiety: slow breathing, regular exercise, and therapy.
• Fever: fluids, rest, and acetaminophen (paracetamol) or ibuprofen at the label dose. No aspirin for children or teenagers.
• A warm, inflamed area: rest, raise the limb, and apply a cool compress. Seek care if it spreads or you have a fever.

Frequently asked questions

What causes a sudden feeling of warmth inside the body?

The most common causes are hot flashes from perimenopause or menopause, the start of a fever, anxiety or panic, alcohol, spicy food and some medicines. An overactive thyroid causes more constant warmth. Warmth with hives, swelling or breathing difficulty may be an allergic reaction and needs emergency care.

Why does one area of my skin feel warm?

A warm patch of skin usually means inflammation from infection, injury, gout or a blood clot. If it is red, swollen, painful and spreading, or you have a fever, see a doctor the same day. A warm, swollen calf can be a blood clot and needs prompt checking.

Why do I feel hot but have no fever?

Common reasons include hot flashes, anxiety, exercise, a warm room, hot drinks or spicy meals, alcohol, medicines and an overactive thyroid. Keep a diary of episodes. If you also have palpitations, weight loss, tremor or night sweats, see a doctor.

Is a warm leg a sign of a blood clot?

It can be. Deep vein thrombosis typically causes warmth, swelling, tenderness and redness or discoloration in one calf or leg. It needs same-day medical assessment. Call 911 if leg symptoms come with sudden breathlessness or chest pain.

Can anxiety make you feel warm?

Yes. Anxiety and panic release adrenaline, which widens blood vessels in the skin and speeds the heart, causing a rush of warmth, flushing and sweating. These episodes usually pass within minutes. Slow breathing can help them settle.