The US Food and Drug Administration said on Tuesday it had sent a warning letter to Amazon.com related to sale of seven unapproved eye drops on the company’s e-commerce platform.

In the letter dated Nov. 13, FDA said Amazon was selling eye drops which have not been recognized as safe and effective for providing temporary relief from eye symptoms such as excessive watery discharge, redness, burning, or pink eye.

The warning to Amazon comes weeks after the agency recommended consumers not to use 26 over-the-counter eye drop products due to risk of infection and some cases of possible vision loss.

Eye products generally pose a greater risk of harm to consumers as they bypass some of the body’s natural defenses, the agency said.

The seven products flagged in the letter to Amazon include Similasan Pink Eye Relief, Can-C Eye Drops, Optique 1 Eye Drops, OcluMed Eye Drops, among others.

In September, FDA warned eight companies, including pharmacy giants CVS Health and Walgreens Boots Alliance, against manufacturing or marketing of certain unapproved eye products.

Privately held Swiss drugmaker Similasan has previously been asked by the agency to meet relevant safety limits for levels of diethylene glycol or ethylene glycol, two common contaminants in some medicines, as they could lead to lethal poisoning at higher levels.

• Reporting by Bhanvi Satija in Bengaluru; Editing by Shounak Dasgupta, of Reuters.