Never take dietary supplements! One patient was so severely impaired by an overdose of vitamin B3 that he was legally blind. The case was reported in the journal of vitreoretinopathy.
In a report from researchers at mount sinai's New York eye and ear hospital, the 61-year-old patient came to the hospital with deteriorating vision in both eyes and was diagnosed as having met the criteria for blindness, according to MedicalXpress. The patient reported a history of severe high blood pressure and hyperlipidemia, and disclosed that she had purchased and taken large amounts of dietary supplements to reduce her risk of cardiovascular disease, without realizing the possible effects on her vision.
Vitamin B3, also known as nicotinic acid, is used to lower high blood fat or cholesterol and is available in both prescription and over-the-counter forms. In general, doctors do not recommend that people buy nicotinic acid on their own. The standard dose is 1 to 3 grams per day, and the maximum dose is 6 grams. However, the patient took a daily dose of 3 to 6 grams for several months after purchasing nicotine from the pharmacy.
According to the clinician, the patient lost most of his vision due to the high dose of nicotinic acid, which caused the retinal macular sac edema. Fortunately, his vision improved significantly within a week of stopping nicotine, and was back to normal after two months.
As this case shows, it's best to consult a professional before taking any dietary supplements or over-the-counter medications. Even though these medications can be purchased without a prescription, that doesn't mean it's safe to take them on your own.