Knee pain after running: common causes, self-care and when to get it checked

Running places repeated load through the knee, and the joint copes with this every day for most people. Pain that appears during or after a run usually means that one of the tissues around the joint has been asked to do more than it was ready for. The knee is made up of bones, ligaments, cartilage and tendons, as Arthritis UK describes, so there are several places where irritation can start.

The most useful first question is where the pain sits. Pain behind or around the kneecap points one way, pain below the kneecap or between the kneecap and shin points another, and a feeling of the knee giving way or catching points to a different group of problems altogether. Describing the exact spot, the movement that triggers it and what you were doing when it began helps a physiotherapist or GP narrow things down quickly.

Most knee pain after running does not mean lasting damage. Arthritis UK states that sore knees are common and not usually a sign of anything serious, although it also says a cause cannot always be found.

The NHS knee pain page groups causes by whether there was an injury, and several of the entries are typical for runners. The table summarises the ones that most often fit running, using the descriptions given by the NHS, Arthritis UK and Patient.info.

• Patellar tendinopathy, sometimes called jumper's knee, is described by Patient.info as a common painful overuse disorder, with eccentric training the treatment of choice.

• Bursitis is listed by the NHS as warm, red knee pain that is made worse by kneeling or bending.

• Osgood-Schlatter disease, according to the NHS, affects teenagers and young adults, with pain and swelling below the kneecap.

Patient.info describes patellofemoral pain as multifactorial. It lists overuse of the knee, reduced strength in the hip abductor muscles with excessive inward movement of the thigh, minor problems with knee alignment, foot problems such as flat feet (although it says whether this is cause or effect is disputed), and repeated minor injuries. Overuse is described as the most significant risk factor.

In practical terms, pain often follows a change: a faster pace, longer distance, a new route with more hills, different shoes or a return after a break. Patient.info notes that pain is often aggravated by running, especially downhill, and by going down stairs. The NHS tendonitis guidance adds that tired muscles, starting a new sport without practice and repeating the same exercise all raise the chance of a tendon problem.

None of this means running itself is harmful to your knees. It means that load and recovery need to stay in balance, and that a knee that has become irritable needs a temporary reduction in what it is asked to do.

The NHS suggests putting as little weight as possible on the knee at first and avoiding standing for long periods. It recommends an ice pack or bag of frozen peas wrapped in a tea towel for up to 20 minutes every 2 to 3 hours, and painkillers such as paracetamol or ibuprofen gel or tablets.

Arthritis UK suggests balancing rest and activity. During the first 24 to 48 hours it advises resting the knee but avoiding long periods without moving, and moving the knee gently for 10 to 20 seconds every hour while awake. After 48 hours it says to try to use the leg more because exercise can help long-term pain, and that low-impact exercise such as cycling and swimming can be useful while recovering from a knee injury. It also advises avoiding heavy lifting until pain has gone down and movement is good.

Sensible footwear matters. Arthritis UK gives supportive shoes and arch supports for flat feet as examples, and the NHS tendonitis page recommends supportive shoes or insoles for exercise, a warm-up and gentle stretching afterwards, and regular breaks from repetitive exercise. Arthritis UK also notes that carrying extra body weight makes joint pain more likely and can make it worse.

If you are unsure whether to carry on running, remember that the sources above advise reducing the load on an irritated knee and seeing a GP or physiotherapist if the pain is not improving within a few weeks.

The NHS says to get advice from NHS 111 now if your knee is very painful, you cannot move it or put any weight on it, it is badly swollen or has changed shape, it locks, gives way or painfully clicks (painless clicking is normal), or you have a very high temperature or feel hot, cold or shivery with redness or heat around the knee, which can be a sign of infection. NHS 111 can say where to be seen, and an urgent treatment centre or minor injuries unit is an option if you need to be seen quickly.

For less urgent problems, the NHS advises seeing a GP if knee pain does not improve within a few weeks. Arthritis UK lists severe pain, a swollen knee, no improvement after a few weeks, being unable to move the knee or put weight on it, and locking, painful clicking or giving way as reasons to see a doctor.

In many areas you can refer yourself to NHS community musculoskeletal (MSK) services for help such as physiotherapy without a GP referral, according to the NHS. Arthritis UK adds that you can also pay to see a physiotherapist privately without a doctor's referral.

Arthritis UK says a doctor will often be able to diagnose a knee problem from your symptoms and a physical examination of the knee, and that tests or scans are occasionally suggested to help confirm a diagnosis, particularly if more specialised treatment may be needed. Patient.info makes a similar point for anterior knee pain: the diagnosis can often be made clinically, and X-rays are mainly considered when there has been trauma.

Treatment depends on the cause. Patient.info says conservative treatment is usually effective and that most people will not need surgery. Its list of measures includes avoiding the trigger activity, simple analgesics, modifying training, strengthening the quadriceps, hip muscles and core, and referral to a physiotherapist. It reports that physiotherapy and hip-strengthening exercises have been shown to reduce pain for up to a year, although the studies are of low quality, that foot orthoses may offer marginal benefit, and that there is insufficient data to show long-term benefit from patella taping.

For tendonitis, the NHS says a doctor may prescribe a stronger painkiller or suggest ibuprofen gel, physiotherapy if the pain is severe or lasts a long time, steroid injections for short-term relief in some severe cases, and, rarely, referral to an orthopaedic specialist if physiotherapy does not help.

The outlook is generally good. Patient.info reports that in younger patients, with early action, adjusted exercise and a stronger quadriceps, the outlook for full functional recovery is very good, and it cites figures of 40% of patients with ongoing symptoms at one year and 85% reporting recovery with no symptoms at 7 years for patellofemoral pain. In older people there may be progression to osteoarthritis.

The NHS says a mild tendon injury treated at home should feel better within 2 to 3 weeks and advises avoiding sport until the tendon has recovered. A gradual return, with a reduced volume of running that you then build on, tends to work better than stopping completely and restarting at full load. Agree the plan with the clinician or physiotherapist who has assessed you, especially if the pain has lasted more than a few weeks.