Reactive arthritis
Reactive arthritis is joint inflammation that begins a few weeks after a gut or genitourinary infection.
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Medicines commonly prescribed for Reactive arthritis
For informational purposes only. Always consult a doctor before using any medicine.
Dosage form: ORAL SOLUTION/SUSPENSION, 600 mg ibuprofenActive substance: ibuprofenManufacturer: Laboratorio De Aplicaciones Farmacodinamicas S.A.Prescription requiredDosage form: ORAL SOLUTION/SUSPENSION, 600 mgActive substance: ibuprofenManufacturer: Farmalider S.A.Prescription requiredDosage form: TABLET, 400 mgActive substance: ibuprofenManufacturer: Laboratorios Normon S.A.Prescription required
Reactive arthritis is joint inflammation that begins a few weeks after a gut or genitourinary infection. There is no infection in the joint itself: that has long since cleared, but the immune system carries on working and by mistake turns on the body's own tissue. Two features of the illness follow from this. The first is that people do not connect a swollen knee with the food poisoning they had a month ago, and arrive at the appointment missing half the story. The second is that antibiotics cannot cure the joint — there is nothing there to kill.
How it starts
One to four weeks usually pass between the infection and the first pains. It affects young adults most, and the gut-triggered form occurs equally in men and women.
The picture is fairly recognisable once you know what to look for:
- only a few joints are involved — one to four, not all of them;
- and they are not symmetrical: one knee hurts, not both;
- the legs are the usual site: knees, ankles, joints of the feet;
- the joint swells, stiffens and feels hot, and the skin over it may look red;
- the joints are stiff in the morning, and it does not wear off at once but over half an hour or longer;
- a separate and very characteristic complaint is heel pain where the tendon attaches to the bone: it hurts to put weight on the foot first thing;
- a toe or a finger may swell along its whole length, like a sausage, rather than at one joint;
- some people get pain in the lower back and buttocks, worst at night and towards morning, which eases with movement;
- there is almost always heavy tiredness and sometimes a slight temperature.
The key to the diagnosis often lies in the past: think back to whether, a month or six weeks earlier, there was diarrhoea, vomiting, food poisoning, stinging on passing urine or an unusual discharge. The infection may have been so mild that you forgot it, and in women a genitourinary infection often causes no symptoms at all.
Not only joints: eyes, waterworks, skin
Reactive arthritis rarely comes alone, and it is worth knowing this in advance so that you do not chase each complaint round a different clinic.
- Eyes. Usually conjunctivitis: redness, sticky lids, a gritty feeling. Unpleasant but not dangerous. In some people, though, the inner layer of the eye becomes inflamed — the eye reddens around the iris, hurts badly, dislikes light, and vision blurs. That needs an eye specialist to look at it within a day, because untreated it can damage sight.
- Passing urine. Stinging, going more often, discharge. One important detail: this inflammation also occurs in the gut-triggered form, so it does not always mean a sexually transmitted infection.
- Mouth. Small ulcers on the lining, usually painless, which is why they go unnoticed.
- Skin and nails. A thick, scaly rash with crusts can appear on the soles and palms, and the nails thicken and crumble. In men there are sometimes painless patches on the head of the penis.
The combination of joint plus eye plus waterworks is far from universal, but where it is present it argues strongly for reactive arthritis.
Why the joint is inflamed if there is no infection in it
The microbes that set it off are quite specific. From the gut side they are the causes of food poisoning: salmonella, shigella, campylobacter, yersinia. From the genitourinary side the main culprit is chlamydia.
What happens next is this: the immune system, having recognised the microbe, goes on reacting after it has been destroyed, and the lining of the joint and the tendon attachments become the target. That is why a culture of fluid taken from an inflamed joint grows nothing — there are no live bacteria in it.
Not everyone who has such an infection develops arthritis: we are talking about a few people in a hundred. A great deal depends on inherited features of the immune system — in people carrying a particular genetic marker the illness occurs distinctly more often and runs more heavily. That also explains why, after the same meal that upset several people, only one of the group ended up with sore joints.
Septic arthritis: what must not be confused with it
There is a condition that looks similar but needs help today rather than next week. That is septic arthritis, where bacteria get into the joint itself and destroy the cartilage within days.
Seek urgent care if:
- one joint has flared suddenly and is hot, red and swollen;
- the pain is severe, the joint can barely be moved, and you cannot put weight on the leg;
- there is a high temperature, shivering and marked weakness at the same time;
- all of this came on quickly — over hours, or a day or two.
The risk is higher if there is a replacement joint there, if the joint was injected recently, if there is a wound or a boil on the skin nearby, and also with diabetes, reduced immunity and injecting drug use. In children and older people there may be no temperature at all — go by the joint.
The only way to settle it is aspiration: a thin needle draws off a little joint fluid, which is examined for bacteria. This should be done the same day, before antibiotics are started. Watching such a joint at home, warming it and waiting to see whether it settles is not an option.
Two other things get confused with a single hot joint: gout, whose attack more often starts at night at the base of the big toe, and arthritis after a tick bite. Gonococcal arthritis is a case of its own — it too follows a sexual infection, but unlike reactive arthritis it is a genuine joint infection and is treated with antibiotics urgently.
What the doctor checks, and why
There is no single test that confirms reactive arthritis. The diagnosis is assembled from the account of a recent infection, the pattern of joints involved, and tests that rule other things out.
The usual set is:
- a blood test for inflammation, plus the markers that help separate this from rheumatoid arthritis;
- urine testing and a swab for chlamydia, and after a recent gut infection a stool culture;
- aspiration of the joint if there is a good deal of fluid: not to find the cause of the arthritis but to exclude a purulent infection and the crystals of gout;
- an ultrasound or X-ray, to see what is happening inside the joint and at the tendon attachments.
Sometimes a test for that genetic marker is offered. It is useful as a supporting argument but proves nothing on its own: plenty of healthy people carry it, and some people with the illness do not.
Treatment is led by a rheumatologist; an eye specialist joins in if the eye is inflamed, and a dermatologist if the skin changes markedly. If a chlamydial infection is found, a sexual partner needs testing and treatment too — otherwise the whole thing repeats.
How it is treated
The mainstay is anti-inflammatory medicines of the non-steroidal group. They relieve the pain and damp down the inflammation itself, and they are taken as a regular course while the joint is active rather than only when it hurts. The choice belongs to the doctor: this group has restrictions in stomach, kidney and heart disease.
If that is not enough, there are further steps:
- injecting a steroid straight into the inflamed joint, which often gives quick and lasting relief, but only once infection inside the joint has been excluded;
- a short course of steroids by mouth when many joints are involved;
- for a drawn-out course, disease-modifying antirheumatic medicines, which act slowly and are prescribed for months;
- antibiotics — but only to treat the infection itself if it is still present. A course of antibiotics does not shorten the arthritis and does not treat the joint, and this is one of the main misunderstandings about the illness.
One part of treatment is separate and underrated: movement. Complete rest quickly leads to stiffness and loss of muscle, so the joint needs a gentle but daily range of movement and, as the inflammation settles, strengthening exercises. A physiotherapist helps to pitch the load correctly and, where the heel hurts, to choose footwear and insoles.
How long it lasts and what you can do
The outlook is good on the whole: in most people everything settles within three to six months and leaves no trace. In some it drags on beyond a year or returns after a new infection. In a minority — chiefly those carrying that genetic marker — it turns into long-running inflammation of the spine and joints that needs continuing follow-up.
While a flare is going on, simple things help:
- cold through a towel on a hot swollen joint, heat on stiff muscles but not on an inflamed joint;
- do not take to your bed: move a little every day, change position, stretch;
- shift activity to what spares the joints — swimming, an exercise bike, walking on the flat;
- comfortable shoes with a soft sole, particularly if the heels and feet hurt;
- take painkillers to the schedule the doctor set, not on an ad hoc basis.
It is worth coming back sooner than planned if a painful red eye that dislikes light appears, if one joint flares badly alongside a high temperature, or if night-time back pain persists for months — the last of these suggests the illness has not retreated but changed form.
Online consultation
A remote appointment is a good way to assemble the half of the story that is usually missing: the doctor will ask in detail what happened in the month or six weeks before the joint pain, which joints are involved and in what way, and whether there are eye, urinary or skin complaints — then say whether this looks like reactive arthritis and which tests are worth having before a face-to-face visit. It is equally useful for going over results you already have, making sense of a prescribed treatment and working out what to do in a flare.
What an online appointment does not settle is worth stating plainly: a single hot joint with a high temperature is not assessed at a distance. That needs examination and aspiration of the joint the same day — start by seeking urgent care, not by writing a message.
This material is for information only and does not replace medical advice.
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