Multiple vitamin overdose occurs when someone accidentally or intentionally takes more than the normal or recommended amount of multi-vitamin supplements.

Any ingredient in a multiple vitamin supplement can be toxic in large amounts, but the most serious risk comes from iron or calcium.

See also: Iron overdose

A variety of muti-vitamin supplements are sold over-the-counter.

• Bladder and kidneys
  • Cloudy urine
  • Frequent urination
  • Increased urine output
• Eyes, ears, nose, mouth, and throat
  • Dry, cracking lips (from chronic overdose)
  • Eye irritation
  • Increased sensitivity of the eyes to light
• Heart and blood
  • Electrical disturbances (arrhythmias) in the heart
• Muscles and joints
  • Bone pain
  • Joint pain
  • Muscle pain
  • Muscle weakness
• Nervous system
  • Convulsions (seizures)
  • Headache
  • Mental changes
  • Mood changes
  • Irritability
• Skin and hair
  • Flushing from niacin (vitamin B3)
  • Dry cracking skin
  • Itching
  • Yellow-orange areas of skin
  • Sun-sensitivity (more likely to sunburn)
  • Hair loss (from long-term overdose)
• Stomach and intestines
  • Appetite loss
  • Constipation (from iron or calcium)
  • Diarrhea
  • Nausea and vomiting
  • Stomach pain
  • Weight loss (from long-term overdose)