3 Rare But Serious Side Effects of Vitamin B12 Supplements

Summary: Vitamin B12 is usually safe and great for your body, but taking high doses—especially through injections—can cause some rare but serious side effects. While many performers and busy people take it for a quick energy boost, high doses can sometimes lead to severe allergic reactions, sudden acne breakouts, or rosacea flare-ups.

If you are treating a severe B12 deficiency, the sudden rush of new red blood cells can drop your body's potassium levels. This condition, called hypokalemia, leads to muscle weakness, fatigue, and an irregular heartbeat. Surprisingly, if you take certain everyday medicines for diabetes (like Metformin) or acid reflux, they can actually lower your B12 levels over time. Always check with a doctor before starting a new supplement to make sure it's right for you!

For more details, see rssapp-verywellhealth-com at verywellhealth.com/vitamin-b12-side-effects-11867695 (opens in new tab)