Knee pain: causes, location guide, relief and red flags

Knee pain is one of the most common aches people get, and in most cases it is not serious. It often comes from a minor strain, overuse, or normal wear of the joint, and it usually settles within a few weeks with simple self-care.

This page is general information to help you understand knee pain and look after it sensibly. It is not a diagnosis. If your pain is severe, follows a serious injury, or you have any of the warning signs further down this page, see a healthcare professional.

What causes knee pain?

Knee pain usually comes from one of two things: an injury or strain, or gradual wear and irritation in and around the joint. The knee is a complex hinge held together by ligaments, cushioned by cartilage, and powered by the muscles of the thigh and calf, so there are several structures that can become sore.

Common causes include:

• Sprains and strains — overstretching the ligaments or muscles, often after twisting, an awkward step, or doing more than usual.
• Osteoarthritis — gradual wear of the joint cartilage, the most common cause of ongoing knee pain in people over about 45. It tends to cause stiffness and aching in one or both knees.
• Tendon irritation (tendinopathy) — overuse of the tendons around the kneecap, common in runners and people who have increased their activity.
• Bursitis — inflammation of the small fluid-filled cushions in the knee, which can make the area warm, swollen, and tender (for example after a lot of kneeling).
• Cartilage or ligament injuries — such as a torn meniscus or a ligament injury, usually after a twist or impact.
• Gout — a sudden, very painful, hot, swollen joint caused by a build-up of uric acid crystals.

In younger people, pain is more often linked to injury or activity; in older people, age-related changes in the joint are more common.

Can the location of knee pain tell me the cause?

Where the pain is can give a rough hint about what's going on, but it is not a diagnosis — the same spot can have several causes. Use this as a starting point, not a verdict.

• Pain at the front of the knee (around or under the kneecap): often linked to the kneecap and its tendons — overuse, "runner's knee," or tendon irritation. This area is also a common spot for pain when going up or down stairs.
• Pain on the inner side (inner knee pain): can come from the inner ligament, the inner part of the cartilage (meniscus), or wear on the inner part of the joint. It is a frequent site for osteoarthritis-related aching.
• Pain on the outer side: may involve the outer ligament or a band of tissue on the outside of the thigh that can rub and become sore, again common in runners and cyclists.
• Pain at the back of the knee: sometimes from tight hamstrings or calf muscles, or from a fluid-filled swelling behind the knee. Persistent or significant swelling at the back of the knee is worth getting checked.

Knee pain when bending — for example when squatting, kneeling, or climbing stairs — is very common and often points to the kneecap or the front of the joint, but it can also occur with general wear and inflammation.

How can I relieve knee pain at home?

For everyday knee pain without a serious injury, the aim is to settle the irritation while keeping the joint gently moving. Rest completely only briefly — prolonged inactivity tends to stiffen and weaken the knee.

Helpful steps include:

• Ease off, but keep moving. Reduce the activity that aggravates it, but try to stay active within comfortable limits. Gentle, regular movement is good for the joint.
• Ice for swelling and pain. Apply an ice pack (or a bag of frozen peas wrapped in a tea towel) for up to 20 minutes. Never put ice directly on the skin. Some people find a heat pack more soothing for stiffness — either is fine.
• Elevate and support. When resting, raise the leg on a cushion to help reduce swelling.
• Sensible pain relief. Over-the-counter painkillers such as paracetamol, or an anti-inflammatory like ibuprofen (including gels rubbed into the area), may ease the pain enough to keep you moving. Use them as directed, for the shortest time needed, and check with a pharmacist or GP if you have other health conditions, take other medicines, or are unsure whether they suit you.

What not to do. Don't push through sharp or worsening pain, and don't return to running, sport, or heavy activity too soon — building back gradually protects the joint. Avoid resting completely for long periods, as that tends to make a stiff knee worse.

What exercises help knee pain?

Gentle strengthening and stretching are among the most effective long-term ways to ease and prevent knee pain, because stronger thigh and hip muscles take load off the joint. The general principle is to build up slowly and stop short of sharp pain — mild discomfort that settles afterwards is usually fine.

At a high level, useful approaches include:

• Strengthening the thigh muscles (the quadriceps and hamstrings), for example with controlled sit-to-stand movements, gentle leg raises, and small squats within a comfortable range.
• Working the hip and buttock muscles, which help control the knee and reduce strain on it.
• Stretching the calves and the front of the thigh to keep the leg moving freely.
• Low-impact activity such as swimming, cycling, or walking, which keeps the joint moving without heavy loading.

If you're not sure where to start, a physiotherapist can give you a tailored programme. In many areas you can refer yourself to NHS physiotherapy without seeing a GP first. Knee pain often goes hand in hand with foot and lower-limb problems, so if you also have heel or arch pain you may find our guide to plantar fasciitis useful, since footwear and the way you walk can affect the whole leg.

When should I see a doctor about knee pain?

See a GP if your knee pain hasn't improved after a few weeks of self-care, keeps coming back, or is interfering with everyday life. New pain that doesn't settle within about six weeks is worth getting assessed.

Seek urgent medical help (for example by calling NHS 111 or going to an urgent care service) if you have any of these:

• You can't put any weight on the knee or can't move it properly.
• The knee has locked and you can't straighten it, or it keeps giving way.
• Severe pain or sudden, significant swelling, especially after an injury, or the knee looks out of shape.
• The joint is hot and red and you feel unwell or have a fever — this can signal infection or a flare of gout and needs prompt assessment.
• A serious injury or impact, such as a fall or sports collision.

These warning signs don't always mean something is badly wrong, but they need a professional to check. This page is background information and not a substitute for advice from a doctor, physiotherapist, or other healthcare professional.