COVID-19 treatment in Thailand turns infant's brown eyes into blue in rare side effect

While most coronavirus treatments come with a set of side effects, the changing of one's eye color is pretty uncommon. However, a 6-month-old born with dark brown eyes experienced the rare symptom after receiving a treatment commonly used for the novel virus. 

The case emerged in Thailand, where the infant was diagnosed with COVID-19 with symptoms such as fever and cough, according to the medical journal Frontiers in Pediatrics. Doctors then prescribed favipiravir, an antiviral treatment approved by the Thai Ministry of Public Health last year to treat children experiencing mild to moderate symptoms.

However, after 18 hours of receiving the dosage, the child's eyes began turning bright blue. The infant's mother reached out to medical professionals and was asked to discontinue the treatment immediately. After a period of five days, the child's eyes turned back to brown.

What did experts say? 

The infant was eventually examined by doctors who found out that the cornea no longer had any blue pigment. While the reason behind the color change has not been ascertained, experts speculate that it “may be due to the drug, its metabolites, or additional tablet components such as titanium dioxide and yellow ferric oxide.”

But studies have long discovered “a direct relationship” between the concentration of favipiravir and the intensity of fluorescence, the emission of absorbed light. The treatment's most common symptoms include diarrhea, mild hyperuricemia (increased levels of uric acid), and neutropenia (low levels of the white blood cell neutrophils). 

While corneal discoloration is rare, it has happened before. According to the New York Post, a man in India experienced the side effect in 2021. The unnamed individual was prescribed favipiravir after medicines such as vitamin C, zinc, vitamin A, vitamin D and ivermectin did not seem effective. Two days after using favipiravir, the 20-year-old noticed that his eyes turned from dark brown to blue.