Two Chinese doctors who recovered form COVID-19 have now been afflicted by another bizzare medical ailment that caused their skin to turn dark.

According to Daily Mail, Yi Fan and Hu Weifeng woke up after recovering only to find their skin had become “very dark.”

The doctors, both 42, had contracted the coronavirus in January while treating patients in Wuhan where the outbreak began late 2019.

Doctors treating them were reported to have said the abnormal skin colour is caused by “hormonal imbalances after their livers were damaged by the virus.”

Daily Mail also quoted Li Shusheng, one of those involved in their care, as attributing the change in skin colour to a type of medicine administered to the patients in the early stages of their treatment.

It did not state the name of the drug, but further quoted the doctor to have said one of its side effects is “the darkening of skin colour.”

Weifeng, whose condition is said to have been worse, has been bed-bound for 99 days, while Fan recovered after he was hooked him to a life-support machine called ECMO.

ECMO procedure, commonly used for long-term respiratory or cardiopulmonary failure, involves re-oxygenating blood removed from a patient’s body and returning it afterwards.

TheCable had reported how two US doctors recovered from the infection after being treated with the experimental blood therapy.