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Reactive arthritis

Reactive arthritis is a type of arthritis in which you develop inflammation in joints after you have had an infection in some other part of the body. For example, after a bad bout of diarrhoea you might develop a sore knee a couple of weeks later. Symptoms commonly last between a few weeks and a few months. Anti-inflammatory medicines usually ease the pain. Other treatments are sometimes needed. This is an unusual condition that would usually be managed by a specialist.

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What is reactive arthritis?

A lot of us get achy joints when we've got a bad cold or the flu. That usually goes away in a day or two. But there is a more serious condition where a joint (usually the knee) becomes very sore and red, a couple of weeks after some other kind of infection in the body.

The infection which triggers reactive arthritis is not actually in the joint, but is usually in the digestive system or urethra (the small tube that urine flows out of).

Reactive arthritis symptoms

Symptoms of reactive arthritis usually develop 2-4 weeks after the infection - often after the triggering infection has gone. For example, you may have had a bout of diarrhoea and being sick (vomiting) a couple of weeks previously which you may even have forgotten about.

Joint symptoms

These usually develop fairly quickly, over a day or so. In some cases they develop more gradually.

  • One or more joints may be affected.

  • The joints in the legs, such as knees, ankles and toes, are the ones most commonly affected. Inflammation of joints at the base of the spine is also common, causing low backache and buttock pain. However, any joint can be affected.

  • Stiffness may develop at first before any pain.

  • Joints near the skin surface, such as the knee, may become quite swollen.

  • The severity of pain and swelling can vary from mild to severe.

  • The tendons and ligaments next to some joints may also become inflamed. The most common site for this is the Achilles tendon at the back of the ankle which may become painful.

  • A whole finger or toe may become swollen, this is called dactylitis. This swollen appearance is sometimes called a sausage finger or sausage toe.

Other symptoms

In addition to joint symptoms, one or more other symptoms develop in up to half of cases. These develop at the same time, just before, or just after the joint symptoms.

  • Inflammation of the urethra (urethritis). Urethritis can cause a discharge which you may see coming from the penis in men, or from the vagina in women. You may also have pain when you pass urine. Note:

    • The triggering infection may be an infection of the urethra, which causes urethritis. In this case, the urethritis comes before the arthritis and other symptoms.

    • Inflammation of the urethra can also develop as a reaction to a gut infection as part of the syndrome of reactive arthritis. In this case, no germs are found in the urethra and it may develop after, or at the same time as, the joint symptoms.

  • Inflammation of the front of the eye (conjunctivitis). This can make your eye look red. However, it is not very painful, does not affect vision and is not serious.

  • Inflammation of a deeper part of the eye (uveitis). This can cause eye pain, redness, and blurring of vision. It is more serious than conjunctivitis.

  • A scaly skin rash on the hands and feet (keratoderma blennorrhagica) occurs in a small number of cases.

  • Inflammation and redness at the end of the penis (circinate balanitis) sometimes occurs. However, it is not usually painful or serious.

  • Mouth ulcers, which are usually painless.

  • Changes to your nails, including thickening and crumbling, are a rare symptom.

  • You may have a high temperature (fever).

  • Weight loss may be a feature.

  • Tiredness can occur.

  • Rarely, heart or kidney problems can develop.

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Reactive arthritis causes

When you have an infection your immune system tries to fight it off. This usually works well and that's why we recover from infections. But sometimes your immune system goes into overdrive and accidentally tries to fight your own body. This is thought to be what happens in reactive arthritis: your body produces antibodies against your own joint. This makes it red, swollen and painful. There isn't actually any infection in the joint itself but your body thinks there is.

Infections that can trigger reactive arthritis include:

  • Infection of the urethra. This is also called urethritis. It is the most common trigger. About 1 in 100 people who have an infection of the urethra also develop reactive arthritis. The urethra is a part of the urinary tract, it is the tube that passes urine out from the bladder. Some sexually transmitted infections can cause urethritis. Infection with a sexually transmitted bacterium called chlamydia is the most common. Symptoms of the infection include a discharge from the urethra and pain when you pass urine.

  • Infection of the gut. This is also called gastroenteritis and is the other common trigger. Various bacteria can infect the gut and cause vomiting and/or diarrhoea. For example, shigella, salmonella, campylobacter and yersinia. These infections are often caused by food poisoning. About 1 in 100 people who have a gut infection with one of these bacteria also develop reactive arthritis.

  • Infection with Chlamydia pneumoniae. This bacterium can cause a respiratory tract infection (causing a cough or a lung infection) and can sometimes be a trigger.

  • Viral infections that can cause a sore throat, cough or skin rash are sometimes the trigger. The infection may be mild and soon forgotten, but it may still trigger an arthritis.

  • No triggering infection can be found in about 1 in 10 cases.

Sometimes people with HIV infection can develop reactive arthritis. This is likely to be because both conditions can be transmitted sexually rather than HIV infection acting as a trigger for reactive arthritis.

Note: the triggering infection is not within the joint itself. An infection within a joint is different and is called septic arthritis. See the separate leaflet called Septic Arthritis for more details.

Risk factors

Reactive arthritis is uncommon. It occurs most often in men aged between 20 and 40 years. This is because they are most at risk of urethral infection from sexually transmitted infections. However, it can occur at any age and in anyone. We are all at risk of getting a gut infection from food poisoning, which may trigger a reactive arthritis.

There is a genetic link too. About 1 in 14 people in the UK have a gene called HLA-B27. About 3 out of 4 people with reactive arthritis have this gene. So, this gene seems to make you more likely to develop reactive arthritis if you have a triggering infection.

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Reactive arthritis diagnosis

No test can confirm that you have reactive arthritis. The diagnosis is based on the typical symptoms which follow an infection. However, tests including blood tests and X-rays may be done to rule out other causes of arthritis, such as gout or rheumatoid arthritis. If there is fluid on your joint a sample of the fluid may be taken to check for other causes of arthritis.


  • You may be asked to give a stool sample (sample of faeces) if a gut infection is suspected as the trigger. However, a triggering gut infection may be gone before the arthritis develops.

  • You (and your sexual partner) may be referred to a genitourinary clinic to check for sexually transmitted infections if urethritis is suspected as the trigger. You should avoid having sex (including oral sex) until you and your partner have completed treatment and follow-up for any genital infection that has been found.

  • Other tests for triggering infections may be done if any are suspected.

  • You may be referred to an eye specialist if your doctor suspects that you have inflammation of the deeper part of the eye (uveitis).

Reactive arthritis treatment

Treating any triggering infection

  • If the trigger is an infection of the urethra, a short course of antibiotics will usually be advised.

  • Gut infections have often cleared on their own by the time the reactive arthritis develops. But, if a stool (faeces) sample shows that a germ is still present then treatment may be advised to clear it.

Note: clearing the triggering infection does not usually alter the course of the arthritis. Once the arthritis is triggered, it will usually run its course well after any infection has gone.

However, some studies suggest that long-term treatment with antibiotics may help to reduce the length of the arthritis in some cases, particularly if chlamydia is the triggering infection. The use of long-term treatment with antibiotics in reactive arthritis is currently being investigated.

Treating the joint symptoms

  • Non-steroidal anti-inflammatory drugs (NSAIDs) ease pain and stiffness. There are many different brands and your doctor will usually prescribe one. There is no best option and some people find that one type suits them better than others. So, if one does not suit at first, another may be fine.

  • Some joints become very swollen. The fluid may be removed by a doctor with a needle and syringe, which can ease the pain. This is called joint aspiration.

  • An injection of steroid medicine directly into a joint is an option if it becomes badly inflamed. Steroids are good at reducing inflammation. Sometimes steroid tablets may be taken by mouth if symptoms are particularly bad.

  • You may need to rest very swollen joints until the symptoms ease. But as soon as you can, it is important to get the affected joints moving and exercising again.

  • Physiotherapy helps to keep the joints moving. It also helps to keep the muscles around affected joints strong if you are not using a joint very much.

  • If symptoms continue for more than a few months, or if other treatments have not worked, you may be advised to take a disease-modifying medicine. These are sometimes called disease-modifying antirheumatic drugs (DMARDs). This aims to reduce the damaging effect on the joints. There are several - for example, sulfasalazine and methotrexate. These medicines have no immediate effect on pain or inflammation. They take several weeks to work. However, they may help to prevent long-term joint damage if symptoms continue.

  • If DMARDS don't work for you, you may be prescribed injections of a biological therapy, also called biologics. Examples of these drugs include etanercept and infliximab.

Treating other symptoms

Outlook (prognosis)

How long does reactive arthritis last?

At the onset of the disease, it is not possible to predict how long it will last.

  • In some cases, the symptoms last just a few weeks.

  • In most cases the symptoms last 3-6 months and then go completely without leaving any long-term problem. After the swelling and inflammation (arthritis) have gone, it is quite common to have niggly pains which continue for several further months.

  • In about 1 in 3 cases the arthritis lasts longer than twelve months. It can sometimes last for years. If joint inflammation continues for six months or more, you are at risk of joint damage which may cause long-term pain and disability. It is in these cases where disease-modifying medication (DMARDs) may be used.

In some people who make a complete recovery, the symptoms return months, or even years, after the first episode. This may be a reaction to a new infection, or symptoms may just flare up for no apparent reason.

Preventing reactive arthritis

if you have had one episode of reactive arthritis, you should take particular care to protect against sexually transmitted diseases and food poisoning which may trigger a further episode.

History of the condition's name

A doctor named Dr Reiter noticed that some people had a 'triad' of symptoms: joint inflammation (arthritis), infection of the urethra (urethritis) and inflammation of the front of the eye (conjunctivitis), all at the same time. The condition was named Reiter's syndrome, after him, but has subsequently become known as 'reactive arthritis'. We know now that reactive arthritis often, but not always, has these three symptoms. In some cases there are additional symptoms (described above) and it may also follow a sexually transmitted infection.

Further reading and references

  • Selmi C, Gershwin ME; Diagnosis and classification of reactive arthritis. Autoimmun Rev. 2014 Apr-May;13(4-5):546-9. doi: 10.1016/j.autrev.2014.01.005. Epub 2014 Jan 10.
  • Ajene AN, Fischer Walker CL, Black RE; Enteric pathogens and reactive arthritis: a systematic review of Campylobacter, salmonella and Shigella-associated reactive arthritis. J Health Popul Nutr. 2013 Sep;31(3):299-307.
  • Morris D, Inman RD; Reactive arthritis: developments and challenges in diagnosis and treatment. Curr Rheumatol Rep. 2012 Oct;14(5):390-4. doi: 10.1007/s11926-012-0280-4.
  • Carlin E, Marzo-Ortega H, Flew S; British Association of Sexual Health and HIV national guideline on the management of sexually acquired reactive arthritis 2021. Int J STD AIDS. 2021 Oct;32(11):986-997. doi: 10.1177/09564624211020266. Epub 2021 May 20.

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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