Hydroxychloroquine: lupus, arthritis and eye monitoring

The NHS describes hydroxychloroquine as a DMARD that calms the immune system or changes the way it responds, used for autoimmune conditions in which the body mistakenly attacks healthy tissue. It is mainly used for conditions causing inflammation, swelling and pain, including rheumatoid arthritis, juvenile idiopathic arthritis and lupus (systemic lupus erythematosus).

It is also used for skin conditions: sarcoidosis, lichen planus and conditions caused or made worse by sunlight such as porphyria cutanea tarda. For the sunlight-related ones it is taken when you know you will be in intense sun, such as during the summer months.

It usually comes as tablets. How much and for how long depends on the reason, but some people take it once or twice a day for at least 6 months. Swallow the tablets whole with a meal or glass of milk and try to take them at the same time each day, such as morning and evening if taken twice.

It takes several weeks to start working and the NHS says to keep taking it unless told to stop. If you have taken it for more than 6 months and do not feel it is helping, speak to your doctor. If you miss a dose, take it when you remember unless the next dose is close. Never take two together.

Common effects are stomach ache, nausea and vomiting, loss of appetite, diarrhoea, headache, an itchy rash and mood changes. It can sometimes cause blurred vision when you first start; if so, do not drive, ride a bike or use machinery until vision returns to normal. If side effects bother you, speak to a pharmacist or doctor and keep taking the medicine unless advised to stop.

Serious effects are rare: anaphylaxis, severe skin reactions with sores, blisters or peeling skin and fever, liver problems (itchy skin, dark urine, pale stools, yellow skin or eyes) and retinopathy, with constant blurred vision, changes in colour vision or sensitivity to light.

Retinopathy is the reason hydroxychloroquine comes with a monitoring plan. The NHS says that if you have taken it for a long time or are at higher risk of eye problems you will have regular eye check-ups to look for early signs. Report constant blurred vision, colour changes or light sensitivity promptly rather than waiting for the next appointment.

People with maculopathy or other eye problems may not be suitable for it, so tell your doctor about any existing eye condition.

Most adults can take it. Children can too, but may not be prescribed it if they do not weigh enough. It may not be suitable if you have liver, kidney, blood or heart problems, maculopathy or other eye problems, diabetes, psoriasis, or have had an allergic reaction to hydroxychloroquine or related medicines such as quinine.

It can be used in pregnancy if needed, and the doctor will prescribe the lowest effective dose. Tell your doctor if you are pregnant or planning a pregnancy. It can often be used while breastfeeding, but check first because very small amounts pass into milk; speak to a professional or 111 about concerns for the baby.

The NHS lists digoxin and other heart medicines, epilepsy medicines, antacids and other indigestion medicines (which may stop it being absorbed), antibiotics such as azithromycin, clarithromycin and erythromycin, and antidepressants. Check with a pharmacist before adding anything new. You can eat and drink normally, and the NHS does not give specific alcohol advice.

Other treatments for the same conditions include methotrexate, sulfasalazine and biological medicines, chosen by a rheumatologist or dermatologist depending on the diagnosis, severity and other health conditions.