A knee injury
Go to A&E (accident and emergency) if you've injured your knee and it has changed shape, it becomes very swollen very quickly, you felt a pop or snap, you can see bone sticking out, or it's bleeding heavily. Don't drive yourself: ask someone to take you, or call 999 if the pain means you can't move your leg to get there.
Get advice from NHS 111 now: you cannot move the knee or put any weight on it, or it is very painful, badly swollen or has changed shape.
Get advice from NHS 111 now: the knee locks, gives way or clicks painfully. Painless clicking is normal.
Get advice from NHS 111 now: a hot, red or swollen knee with sudden severe pain, a very high temperature, or feeling hot, cold or shivery. This can be a joint infection.
A possible broken bone
You hurt your knee and cannot take 4 steps, or you are 55 or over and have injured it: get it checked the same day for a broken bone.
A possible torn knee tendon
A pop or tearing feeling at the front of the knee after a fall, a jump, a landing or a heavy squat, then you can't straighten the knee or lift the straight leg, there's a dent above or below the kneecap, or the kneecap sits higher or lower than on the other side. Go to A&E or an urgent treatment centre, or get help from NHS 111, as our knee pain when squatting guide explains. In the US, go to urgent care or the emergency department.
A hip after a fall
Call 999 or go to A&E for severe hip pain after a fall or injury, if you can't walk or put weight on your leg, or for tingling or loss of feeling in your hip or leg after an injury. Ask for an urgent GP appointment or get help from NHS 111 for severe hip pain that started suddenly without a fall, a hip that's swollen and feels hot, skin around it that has changed colour, or hip pain with feeling generally unwell and a high temperature.
A clot in the leg
Same day (urgent GP appointment or NHS 111): throbbing pain in one leg (rarely both), usually the calf or thigh; swelling in one leg (rarely both); red, blue or darkened skin around the painful area, which may be harder to see on brown or black skin; or swollen veins. It could be a blood clot (deep vein thrombosis, DVT), which is more likely while you're moving about much less than usual or after a hospital stay.
Also call 999 for pain and swelling in one leg with breathlessness or chest pain: it can be a blood clot that has reached the lungs.
Source 35
Back pain with leg symptoms
Call 999 or go to A&E: loss of feeling or numbness around the genitals or bottom, new trouble peeing or controlling your bladder or bowels, changes in genital sensation during sex or problems with erections or orgasm, or pain, tingling, weakness or numbness in both legs. These are signs of cauda equina syndrome, which needs treating in hospital urgently. Don't drive yourself.
See a GP if pain spreading down a leg hasn't improved after a few weeks of home treatment, is getting worse or stops your normal activities. Sciatica on both sides, or weakness or numbness in both legs that's severe or getting worse, is a 999 call or a trip to A&E.
Older adults: stop and call 999
Chest pain, pressure or tightness that spreads to the arm, neck or jaw, or does not go away when you stop, especially with breathlessness, sweating, feeling sick, or grey or pale skin.
After a fall: a possible injury to the head, neck, back or hip, or not being able to get up.
Older adults: stop for today and contact your GP or NHS 111
Dizziness, light-headedness, unusual breathlessness, clamminess or chest tightness that settles when you stop.
Any fall or near-fall, new unsteadiness, or a new fear of falling: ask about a falls assessment.
See a GP
Knee pain that has not improved within a few weeks of looking after it at home. Many areas offer NHS physiotherapy without a GP referral.
See a GP if hip pain stops you doing normal activities or affects your sleep, is getting worse or keeps coming back, hasn't improved after 2 weeks of treating it at home, or you have hip stiffness for more than 30 minutes after waking up.
Stop and get medical help
If you get chest pain or pressure, feel faint or dizzy, are unusually breathless, or your heart races or beats irregularly during exercise, as our plans advise.
Call 999 (911 in the US)
For chest pain that comes on suddenly and doesn't go away, feels tight or like squeezing, spreads to your arms, neck, jaw, stomach or back, or comes with sweating, feeling sick, light-headedness or breathlessness; severe difficulty breathing; someone who faints while exercising; palpitations that don't go away, or come with chest pain, shortness of breath or feeling faint; or a headache that starts suddenly and is extremely painful, especially while lifting or straining, or comes with numbness or weakness, difficulty speaking or loss of vision. The NHS says a bleed on the brain may be more likely when lifting something heavy. Don't drive yourself to A&E.
Ask for an urgent GP appointment or call NHS 111
Ask for an urgent GP appointment or get help from NHS 111 for a headache that's triggered or made worse by coughing, sneezing, bending down or exercising. In the US, contact your doctor or urgent care.
During any session
Stop straight away if you feel any pain or become unwell, the NHS says, and contact 111 if your symptoms worry you or don't go away.
A dull ache in your muscles for a day or two after something new is normal. Joint pain that's sharp, gets worse during a set or lingers into the next day means switching to the easier option, and seeing a GP or physiotherapist if it carries on (our plans' rule). Our muscle soreness guide has more.
Check first
Speak to your GP first if you haven't exercised for some time or have medical conditions or concerns, as the NHS advises. Get advice before heavy lifting or hard straining work if your blood pressure is uncontrolled, or you have heart disease or chest pain when you're active, a pacemaker or defibrillator, diabetic eye disease, glaucoma, a hernia, recent eye or tummy surgery, or you're pregnant, as our breathing guide lists. After a recent shoulder dislocation or shoulder surgery, follow our shoulder dislocation guide or your surgical team first.
Speak to a GP first if you haven't exercised for some time, or if you have a medical condition or concerns. Get advice first, too, if you have a health problem, an injury or symptoms, have recently had a heart attack or an operation, or are pregnant or have recently given birth.
Source 3
Hernia
See a GP if you think you have a hernia, a bulge or lump that may get bigger when you strain and smaller when you lie down. Get help from NHS 111 if you have a hernia and pain in or around it, a bloated tummy, you feel or are sick, you're vomiting blood or your vomit looks like coffee grounds, you're constipated, you have a high temperature or feel hot, cold or shivery, or you've suddenly become confused. Call 999 or go to A&E for a femoral hernia (a small lump at the top of your thigh, in your groin) with very bad tummy pain, sickness, being unable to fart or poo, a high temperature or sudden confusion.