healthHealth and Medicine

Baby's Brown Eyes Turn Blue In Rare Complication Of COVID-19 Antiviral Treatment

In the sunlight, the boy's eyes shone blue.

James Felton

James Felton

James Felton

James Felton

Senior Staff Writer

James is a published author with four pop-history and science books to his name. He specializes in history, strange science, and anything out of the ordinary.

Senior Staff Writer

A child's eyes, glowing under UV light.

The infant's eyes were previously brown.

Image credit: Jiravisitkul et al, Frontiers in Pediatrics 2023 (CC BY 4.0)

A six-month-old's eyes turned an unusual shade of blue, in what doctors believe was a rare complication from a treatment for COVID-19.

The boy was first brought to doctors following the development of a cough and fever, before an antigen test confirmed that he had COVID-19. He was prescribed favipiravir by the doctors, which is normally used to treat influenza. The antiviral medication is sometimes prescribed for COVID-19 in Japan and Thailand, though evidence suggests it has little positive effect on outcomes for patients with non-severe, early stages of the disease. However, other research indicates patients under 60 who have been admitted to hospital for COVID-19 may see some benefit.


Mild diarrhea and elevated uric acid in the blood are more common side effects of favipiravir use, but 18 hours after beginning the treatment, the boy's mother noticed his eyes turned a bright blue color in sunlight. The rare side effect had been reported previously, including in the case of one 20-year-old man. In both cases, when treatment was discontinued the patients' eyes returned to their usual color.

In their discussion, the baby's doctors note that "favipiravir has also been shown to cause fluorescence in human hair and nails."

"This adverse effect may be due to the drug, its metabolites, or additional tablet components such as titanium dioxide and yellow ferric oxide," the team wrote. "Studies have shown that the active phosphorylated metabolite of favipiravir is found in human plasma and that there is a linear correlation between its concentration and the intensity of fluorescence."

Further investigations in the lab showed that the drug was fluorescent under UV light. The team highlight in the report recent concerns around the safety and efficacy of favipiravir in treating COVID-19.


"The reported adverse event, although rare, should be taken seriously and closely [monitored] in future cases," they conclude. "Further studies are needed to determine the incidence of these adverse [effects] and its potential long-term consequences on corneal health."

The study is published in Frontiers in Pediatrics.

[H/T: LiveScience]


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