Reactive arthritis: symptoms, treatment, how long it lasts and in children

The NHS says common symptoms are sore, stiff and swollen joints, skin around painful joints that feels hot and looks red (redness can be harder to see on black and brown skin), and feeling very tired. It usually affects the knees and feet, but the hands, elbows, spine and tendons around joints may also be affected.

Arthritis UK adds that you may notice your knees, ankles or toes suddenly become swollen, stiff and painful to move, or the swelling may appear gradually over a few days. It can cause sausage-like swelling of a whole finger or toe (dactylitis) and inflammation of the Achilles tendon.

Other symptoms are not about the joints. The NHS lists mouth ulcers, pain when peeing, flaky skin usually on the soles or palms, a grey or white patchy rash on the penis, sticky watery eyes (conjunctivitis) and sore red eyes with sensitivity to light and blurry vision. Arthritis UK also lists weight loss, fever and diarrhoea.

• Sore, stiff, swollen joints, usually knees and feet

• Hot or red skin over affected joints

• Feeling very tired

• Mouth ulcers and pain when peeing

• Flaky skin on the soles or palms

• Sticky, watery eyes or sore red eyes sensitive to light

• Sausage-like swelling of fingers or toes

The NHS says treatment might include medicines that reduce inflammation, such as NSAIDs or steroids; DMARDs (disease-modifying anti-rheumatic drugs) or biological therapies, which reduce inflammation by changing the way the immune system works; physical therapy such as physiotherapy; and antibiotics if you still have the infection that may have caused the reactive arthritis.

Arthritis UK describes three approaches. First, treating the infection if there are still signs of it. Antibiotics will not treat the joint inflammation but should get rid of the bacteria, and antibiotic treatment should not last longer than four weeks. Second, treating the inflammation: NSAIDs such as ibuprofen or naproxen at the lowest effective dose for the shortest time, a steroid injection into a joint or a muscle, or short courses of low-dose steroid tablets. Third, if symptoms are still bad after a few weeks, DMARDs such as sulfasalazine and occasionally methotrexate or azathioprine, which Arthritis UK says can take between six weeks and six months to work.

Eye involvement is treated separately. Conjunctivitis is often treated with eye drops or ointment, and more severe inflammation such as iritis or uveitis may need steroid eye drops under an eye specialist.

Arthritis UK (formerly Versus Arthritis) describes reactive arthritis as a type of inflammatory arthritis that can affect your joints after an infection somewhere else in your body, such as a tummy bug, diarrhoea or a throat infection. It is sometimes called Reiter syndrome. Arthritis UK says that unlike other types of inflammatory arthritis, for many people it lasts a relatively short time.

It is called reactive because the joints react to an infection elsewhere. The joint itself is not infected, which is why antibiotics treat the original infection and do not cure the arthritis.

Arthritis UK says reactive arthritis can affect people of any age, including children. The main trigger is the same: an infection elsewhere in the body, such as a stomach upset or throat infection, with joint symptoms following later.

A child with a hot, swollen or painful joint, a limp or who is feverish needs to be assessed promptly by a GP or NHS 111 because other causes such as a joint infection must be ruled out. The NHS says to ask for an urgent GP appointment or call 111 for sore joints with a high temperature or sore joints with conjunctivitis or vision problems. Children with persistent joint swelling may be referred to a children's rheumatology team.

The NHS says reactive arthritis usually goes away after 6 months, but for some people it can come back or lead to another type of arthritis that needs long-term treatment, such as osteoarthritis or ankylosing spondylitis. Arthritis UK says for many people it lasts around three months to a year and that it usually clears up within six months without leaving lasting problems.

Some people have a longer course. Arthritis UK says some find it lasts longer and can have random flare-ups years after first getting it, and that a small number of people develop another type of arthritis needing long-term treatment. Most people find they have good days and bad days.

The NHS says reactive arthritis can happen after an infection that is usually in your stomach, such as food poisoning, or after a sexually transmitted infection such as chlamydia. Arthritis UK lists stomach upsets, diarrhoea and other gut infections, throat infections usually caused by streptococcus bacteria, slapped cheek syndrome and glandular fever.

It is not yet known exactly why infections trigger it. Arthritis UK says it is linked to a gene called HLA-B27, which about 1 in 10 people in the UK carry, and people with the gene seem more likely to develop reactive arthritis and to get it more than once.

The NHS says reactive arthritis can be difficult to diagnose because several other conditions can have the same symptoms, so you will usually need a range of tests. These might include a blood test, tests on a urine sample or a genital swab, tests on a small amount of fluid removed from a painful joint with a needle, and an X-ray, MRI or ultrasound scan. You might be referred to a rheumatologist, an ophthalmologist if your eyes are affected or a dermatologist if your skin is affected.

Arthritis UK says there is no specific test. Your doctor will consider whether you have recently had an infection that could be linked to the sudden joint pain, and whether you have other symptoms such as a rash on the palms or soles or red painful eyes. Blood tests help rule out conditions such as rheumatoid arthritis, psoriatic arthritis, Behçet's syndrome and gout.

The NHS suggests getting plenty of rest but trying to move around every day to stop joints getting stiff, doing stretching and strengthening exercises when joints are not swollen, using cold packs wrapped in a towel on sore swollen joints and heat packs on sore stiff muscles, taking painkillers recommended by your doctor, and following your care team's advice on what to do in a flare-up.

Arthritis UK says fatigue plays a major role and that bed rest can do more harm than good. On diet, it says there is no specific diet proven to help reactive arthritis, but a well-balanced diet is important for general health.

The NHS says to ask for an urgent GP appointment or get help from NHS 111 if you have severe pain and swelling in just 1 joint that started suddenly, pain that is not controlled with simple painkillers such as paracetamol, skin around a joint that feels hot to touch or is red, sore joints with a high temperature or feeling hot, cold or shivery, sore joints with conjunctivitis or sore eyes and problems with your vision, or sore joints with pain when you pee, discharge from the penis or vagina, or a rash or sores on the genitals.

See a GP if you have swollen, painful joints that are unusual for you. A hot, red, suddenly swollen single joint can be a joint infection, which needs same-day assessment.

The usual route is through a GP, who can arrange blood tests and refer you to rheumatology, ophthalmology or sexual health services where needed. If a sexually transmitted infection may be the trigger, sexual health clinics provide confidential testing and treatment.

Private rheumatology can offer quicker appointments, but the same tests and medicines apply. A hot single joint or eye symptoms should be seen urgently through NHS 111 or A&E rather than waiting for a private appointment.