What are the side effects of Hydroxychloroquine?

As such, side effects may be less likely to occur and are unlikely to result in significant adverse events. These risks will be assessed in every participant.

Common (less than 10% of patients):

• abdominal pain
• decreased appetite
• diarrhoea
• feeling sick
• vomiting
• mood changes
• skin rash

Uncommon (less than 1% of patients):

• hypoglycaemia (low blood sugar)
• loss of hair (alopecia)
• worsening of eyesight
• blurred vision
• double vision anxiety
• leg or arm weakness
• tingling or numbness
• seizures
• ringing in the ear (tinnitus)
• feeling dizzy
• sensation of unsteadiness or spinning (vertigo)
• low blood or platelet count

Hydroxychloroquine is also associated with other potential ophthalmic side effects including reduced visual acuity, reduced peripheral vision and nocturnal visual impairment.

However, these side effects are associated with prolonged use of hydroxychloroquine (>5 years) and the Royal College of Ophthalmologists advise annual screening for retinal disease for treatment durations of 5 years or longer.

There is also a risk of QT prolongation associated with hydroxychloroquine use, but this risk is extremely low when the duration of hydroxychloroquine treatment is short-term (as in the current trial) and at the doses used in this trial.