Safety and side effects

Red yeast rice can cause mild side effects, including:

• Stomach pain.
• Heartburn.
• Gas.
• Headache.
• Feeling dizzy.
• Upset stomach.

The monacolin K in red yeast rice has the same chemical structure as the prescription cholesterol-lowering medicine lovastatin. The supplement and man-made medicine can have similar side effects that are more serious. These may include liver, muscle, and kidney issues.

Don't take red yeast rice if you're pregnant, trying to become pregnant, or breastfeeding.

Red yeast rice supplements also could have citrinin in them. Citrinin is a toxin that can harm the kidneys. An analysis of 37 red yeast rice supplements found that only one had citrinin at safe levels.