Vitamin A Hypervitaminosis (acute and chronic)

Understanding Vitamin A Overdose

Excessive intake of vitamin A is rare and usually associated with the consumption of supplements rather than foods rich in vitamin A.

There are two types of vitamin A overdose:

  1. Acute and chronic.
  • Acute overdose is rare and occurs when adults consume more than 660,000 international units (200,000 micrograms) of vitamin A in a single dose, and for children, more than 300,000 international units.
    Prominent symptoms of acute vitamin A overdose include:
  • Nausea.
  • Vomiting.
  • Dizziness.
  • Blurred vision.
  • In cases of very high doses, drowsiness, fatigue, frequent vomiting, stomach pain, and neurological disorders may occur. However, the acute form disappears quickly after discontinuing vitamin A supplements.
  • Chronic vitamin A overdose results from long-term high-dose therapy, where the patient consumes a large dose daily for a period ranging from 6 to 15 months.
    Early symptoms of chronic overdose include:
  • Sparse and rigid hair growth.
  • Eyebrow thinning.
  • Dry and rough skin.
  • Dry eyes and cracked lips.
  • Over time, this may progress to severe headaches, pseudo-tumor cerebri (false swelling in the brain), and general weakness. In some studies, consuming large amounts of vitamin A has been linked to bone fractures in the context of osteoporosis in men and women after menopause.

If you notice similar symptoms, consult your doctor. Do not self-medicate – it poses a risk to your health!

In the first trimester of pregnancy, the active form of vitamin A (retinoic acid) negatively affects the fetus and can lead to spontaneous abortion and developmental deformities, such as cleft lip and palate, major blood vessel inversion, and craniofacial anomalies.

The upper limit for safe vitamin A intake during pregnancy is approximately 10,000 international units daily (about 3,000 micrograms).