Skin flushing is a condition characterized by sudden redness and warmth of the skin caused by dilation of small blood vessels near the surface. It is most commonly triggered by excessive intake of nicotinic acid (vitamin B3/niacin) from supplements or medications, though hormonal changes and certain medical conditions can also cause it. The Vitamin B3 blood test is the most important test for diagnosing niacin-induced flushing and determining appropriate treatment.
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Skin flushing is caused by the rapid dilation of small blood vessels near the skin surface, which increases blood flow and creates visible redness and warmth. The most common trigger is excessive nicotinic acid (vitamin B3/niacin) from supplements or cholesterol-lowering medications, which releases prostaglandins that widen blood vessels. Other causes include hormonal fluctuations during menopause, certain medications like calcium channel blockers, alcohol consumption, spicy foods, emotional stress, rosacea, carcinoid syndrome, and mastocytosis.
The Vitamin B3 blood test is the most important test for skin flushing because it directly measures niacin and nicotinic acid levels that commonly trigger flushing episodes. Elevated vitamin B3 levels indicate whether your supplement dosage or cholesterol medication is causing excessive blood vessel dilation and facial redness. This test is particularly essential if you take niacin supplements for cholesterol management or cardiovascular health, as it helps your doctor adjust dosages to reduce flushing while maintaining therapeutic benefits. If vitamin B3 levels are normal, your healthcare provider may recommend additional tests to investigate hormonal imbalances, carcinoid tumors, or allergic reactions.
You should get tested if you experience frequent or severe flushing episodes that interfere with daily activities, especially if you take niacin supplements or cholesterol medications. Testing is important when flushing occurs alongside other symptoms like diarrhea, wheezing, rapid heartbeat, or abdominal cramping, which may indicate carcinoid syndrome or other serious conditions. You should also get tested if flushing persists despite stopping suspected triggers, if it suddenly worsens without explanation, or if you are considering starting niacin therapy and want to establish baseline vitamin B3 levels.
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What this means
Your testosterone levels are slightly below the optimal range. While this is not necessarily cause for concern, it may contribute to occasional fatigue, reduced motivation, or lower muscle mass over time.
Recommended actions
Increase resistance or strength training
Prioritize 7–8 hours of quality sleep per night, try to reduce stress
Include more zinc- and magnesium-rich foods (like shellfish, beef, pumpkin seeds, spinach)
Consider retesting in 3–6 months
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