Free health tool
Symptom Checker – Understand Possible Causes (Educational Tool)
Private — nothing you enter is stored or sent · Updated Jan 2026
Or scroll through all symptoms below.
Headache
Common, usually minor causes
Tension headache, dehydration, too little sleep, eye strain, caffeine withdrawal, a cold or flu, migraine.
Get emergency help now if
A sudden, severe headache that peaks within a minute (“worst ever”); headache with a stiff neck, fever and a rash that does not fade under a glass; after a head injury; with slurred speech, face drooping, weakness or confusion.
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
Headaches that keep coming back, wake you from sleep, get worse over weeks, or started after age 50.
Chest pain
Common, usually minor causes
Strained chest muscles, heartburn/acid reflux, anxiety or a panic attack, a chest infection.
Get emergency help now if
Chest pain that feels heavy, tight or crushing, or spreads to the arm, jaw, neck or back — especially with sweating, sickness or breathlessness. Call 911 / 999 / 112 straight away: it could be a heart attack.
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
Chest pain that comes on with exercise and eases with rest, or keeps returning.
Shortness of breath
Common, usually minor causes
Exercise, anxiety, a chest infection, asthma, being out of condition, anaemia.
Get emergency help now if
Severe breathlessness at rest, blue or grey lips, chest pain, confusion, or sudden breathlessness after surgery, a long flight or with a swollen calf (possible blood clot).
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
Breathlessness that is gradually getting worse, or a cough that lasts more than 3 weeks.
Fever
Common, usually minor causes
Viral infections (colds, flu, COVID-19), ear or throat infections, urinary infections.
Get emergency help now if
Fever with a rash that does not fade under a glass, stiff neck, confusion, fits, or difficulty breathing; any fever in a baby under 3 months (38°C / 100.4°F or more).
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
Fever lasting more than 3 days (adults), or you are pregnant, over 65 or have a weak immune system.
Cough
Common, usually minor causes
Colds and flu, post-nasal drip, asthma, acid reflux, smoking, some blood-pressure tablets (ACE inhibitors).
Get emergency help now if
Coughing up a lot of blood, severe breathlessness, or chest pain.
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
A cough lasting more than 3 weeks, coughing up any blood, weight loss, or a change in a long-standing smoker’s cough.
Sore throat
Common, usually minor causes
Viral infections (most common), tonsillitis, strep throat, dry air, acid reflux.
Get emergency help now if
Difficulty breathing or swallowing saliva, drooling, a muffled voice, or a very swollen neck.
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
A sore throat that lasts more than a week, very high temperature, or white patches with no cough (possible strep).
Stomach (abdominal) pain
Common, usually minor causes
Indigestion, trapped wind, constipation, a stomach bug, period pain, irritable bowel syndrome, anxiety.
Get emergency help now if
Sudden severe pain, pain with vomiting blood or passing black/bloody stools, a rigid tender tummy, or pain in pregnancy with bleeding.
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
Pain that keeps returning, pain after eating with weight loss, or a change in bowel habit for more than 3 weeks.
Nausea and vomiting
Common, usually minor causes
Stomach bugs, food poisoning, motion sickness, early pregnancy, migraine, anxiety, some medicines.
Get emergency help now if
Vomiting blood or “coffee grounds”, severe tummy or head pain, signs of dehydration in a baby (few wet nappies, drowsy), or after a head injury.
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
Vomiting for more than 2 days (adults) or 24 hours (children), or you cannot keep fluids down.
Dizziness
Common, usually minor causes
Standing up too fast, dehydration, inner-ear problems (vertigo), anxiety, low blood sugar, some medicines.
Get emergency help now if
Dizziness with face drooping, arm weakness, slurred speech, sudden loss of vision, chest pain or fainting.
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
Dizziness that keeps returning or affects your balance or hearing.
Tiredness (fatigue)
Common, usually minor causes
Poor sleep, stress, low mood, too little activity, anaemia, an underactive thyroid, recovering from a virus.
Get emergency help now if
Tiredness with chest pain, severe breathlessness, or thoughts of harming yourself.
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
Tiredness lasting more than 4 weeks without a clear reason, with weight loss, or with heavy periods.
Back pain
Common, usually minor causes
Muscle strain, poor posture, long sitting, lifting badly, stress.
Get emergency help now if
Back pain with numbness around the genitals or bottom, new trouble peeing or loss of bowel control (possible cauda equina), or after a serious fall.
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
Back pain that is no better after 4–6 weeks, is worse at night, or comes with fever or weight loss.
Pain when peeing
Common, usually minor causes
Urinary tract infection (UTI), thrush, sexually transmitted infections, irritation from soaps.
Get emergency help now if
Pain with high fever, shivering, pain in the side or back (possible kidney infection), or confusion in an older person.
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
Any UTI symptoms in pregnancy, men, or children, or UTIs that keep coming back.
Peeing more often
Common, usually minor causes
Drinking more (especially caffeine or alcohol), UTI, pregnancy, overactive bladder, an enlarged prostate.
Get emergency help now if
Very thirsty and peeing a lot with vomiting, confusion or fast breathing (possible diabetic emergency).
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
Needing to pee a lot at night, a weak flow, or peeing more along with thirst, tiredness and weight loss.
Heavy or painful periods
Common, usually minor causes
Normal variation, fibroids, endometriosis, adenomyosis, PCOS, an IUD (coil).
Get emergency help now if
Soaking a pad or tampon every hour for several hours, feeling faint, or severe pain with a positive pregnancy test.
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
Periods that stop you doing normal things, bleeding between periods or after sex, or bleeding after menopause.
Skin rash
Common, usually minor causes
Eczema, contact dermatitis, heat rash, hives, viral rashes, fungal infections.
Get emergency help now if
A rash that does not fade when you press a glass on it, with fever; swelling of the lips, tongue or throat; blistering and peeling skin.
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
A rash that spreads, lasts more than 2 weeks, or a mole that changes shape, size or colour.
Racing heart and panic
Common, usually minor causes
Anxiety or a panic attack, caffeine, dehydration, overactive thyroid, some medicines.
Get emergency help now if
Palpitations with chest pain, fainting, or severe breathlessness.
Call 911 (US) · 999 (UK) · 112 (EU)
See a doctor soon if
Palpitations that happen often, last a long time, or come with dizziness; panic attacks that keep returning.
How this works
This guide lists the most common everyday causes of 16 symptoms and, more importantly, the warning signs that mean you should get help today. It is written from NHS, CDC and Mayo Clinic patient guidance.
Good to know
- It cannot diagnose you and does not replace a doctor, pharmacist or nurse.
- In the UK, NHS 111 online can tell you where to go. In the US, call your doctor or an urgent-care line.
- If you are ever unsure whether it is an emergency, treat it as one.
This tool gives general information only and is not a diagnosis. Nothing you enter leaves your browser.