Niacin, also known as vitamin B3, is often used to lower cholesterol and manage high blood fat levels (hyperlipidemia). While it can be effective, taking too much niacin can lead to serious side effects, including eye damage.

A recent study from the New York Eye and Ear Infirmary of Mount Sinai highlights the dangers of self-prescribing high doses of niacin, with one case leading to temporary blindness.

A Case of Vision Loss from Niacin Overuse

The study focused on a 61-year-old man who developed severe blurry vision over the course of a month. His vision had worsened so much that he was nearly legally blind when he visited the hospital.

• His vision was 20/150 in one eye and 20/100 in the other, meaning he could barely read the largest letters on an eye chart.
• At first, he only mentioned his history of high blood pressure and cholesterol but didn’t tell doctors about his supplement use.

Later, he revealed that he had been taking 3 to 6 grams of niacin daily for several months, hoping to reduce his heart disease risk. He had bought the supplement over the counter, unaware of the risks.

How Niacin Affected His Eyes

Doctors explained that the recommended dose of niacin for cholesterol management is between 1 and 3 grams per day. Even though 6 grams is the absolute maximum, such high doses should only be taken under medical supervision.

Over-the-counter niacin is widely available, but self-treatment without a doctor’s guidance can be dangerous.

Using advanced imaging technology, the medical team diagnosed him with a rare condition called niacin-induced cystoid maculopathy.

This condition causes swelling in the macula, the part of the eye responsible for sharp, detailed vision. The excess niacinled to fluid buildup in his retina, resulting in blurry vision.

A Reversible Condition with Proper Care

Fortunately, doctors caught the problem early, and his condition was reversible. They immediately advised him to stop taking niacin.

• One week later, his vision started improving.
• Two months later, the swelling had completely disappeared, and his eyesight returned to 20/20.

A Warning About High-Dose Supplements

This case serves as a reminder that just because a vitamin is available without a prescription doesn’t mean it’s completely safe.

Taking supplements in high doses—without medical supervision—can lead to serious health risks, including potential long-term eye damage.

Key takeaways:
Always consult a doctor before taking high-dose supplements.
Be aware that some vitamins can cause serious side effects at excessive doses.
If you experience sudden vision changes, seek medical help immediately.

The study, led by Dr. Richard Rosen, was published in the Journal of VitreoRetinal Diseases. It highlights the importance of responsible supplement use and the need for medical guidance when managing health conditions.

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