Hydroxychloroquine

What it is

Hydroxychloroquine is an antimalarial that also acts as a slow immune modulator, raising the pH inside cellular compartments and interfering with antigen processing and inflammatory signalling. Its effect builds over weeks to months rather than days. It is used for autoimmune inflammation and is prescription-only.

Used for

• Autoimmune inflammation

What to know while taking it

It is taken with food, which softens the nausea and stomach upset that are its commonest nuisance. It accumulates in the retina over years, so a baseline eye examination and regular follow-up checks are part of the treatment, not an optional extra. It can prolong the QT interval, which matters alongside other heart-rhythm or QT-prolonging medicines. Glucose, ALT and white cell count may be checked during treatment, for blood sugar, liver and blood-count effects respectively.

When to see a doctor

Blurred vision, difficulty reading, missing patches in the field of view or altered colour perception mean see a doctor promptly. Fainting, palpitations or an irregular heartbeat, and symptoms of low blood sugar such as sweating, shakiness or confusion, also warrant medical review.

Worth knowing

• Needs regular eye checks
• Can prolong the QT interval

Markers to watch

• Glucose
• ALT
• White blood cells