Which of the following is a common side effect of niacin?

• A. Drowsiness and weight gain
• B. Cough and throat irritation
• C. Hair loss and night sweats
• D. Flushing, GI distress, skin rashes, pruritus, and increased blood glucose

Answer: (D)

Niacin’s most recognizable and common adverse effects are related to the skin and metabolism. The flushing you get after taking niacin is due to prostaglandin-mediated widening of skin blood vessels, often accompanied by itching. This same dose-dependent reaction is a hallmark of niacin use, and many people notice it as a warm, flushed feeling on the face and neck. Beyond flushing, GI distress and skin reactions like rashes and itching frequently occur, especially at higher doses. Niacin can also affect glucose metabolism, leading to increased blood glucose levels, which is why this is a notable potential side effect with higher-dose therapy. The other symptom clusters listed don’t align with niacin’s typical side-effect profile, which is why the option describing flushing, GI distress, skin rashes, pruritus, and increased blood glucose best matches what niacin commonly causes.