Side Effects of High Doses of Vitamin D

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Vitamin D is a fat soluble vitamin primarily obtained by the body from exposure to sunlight. Its main function is to maintain healthy levels of phosphorus and calcium in the blood. Vitamin D is essential to bone health and helps prevent several conditions and diseases. Vitamin D is in certain foods such as eggs, cod liver oil, dark-colored fish and fortified milk and is available in supplements. It may be referred to by other names such as ergocalciferol (vitamin D-2 ), calciferol, or cholecalciferol (vitamin D-3), reports the Medline Plus website. As with all medications, herbs or supplements, take care to avoid side effects.

Side Effects

Vitamin D is mostly well tolerated, according to the PDR Health website, but excess amounts may cause weakness, nausea, bone pain, headache, vomiting, loss of appetite, weight loss, elevation of cholesterol levels, itchiness, reduced libido, excess urination and increased thirst. Additional side effects are reported by Medline, such as dry mouth, ringing in the ears, vertigo, dizziness and calcium deposits found in the organs in susceptible individuals.

Serious Side Effects

Vitamin D in high amounts may cause chest pain, tightness, hives, difficulty breathing, rash or swelling, reports the PDR Health website. These may be signs of an allergic reaction and require immediate medical attention.

Adverse Reactions

High doses of vitamin D may cause several adverse reactions, according to, including life-threatening impairment of the kidneys. In people with CNS (central nervous system disorder), high doses may cause mental retardation. High doses may also cause calcification throughout the body’s tissues and organs, including the heart, blood vessels and lungs.

Warnings and Contraindications

Speak to your doctor before using vitamin D if you are pregnant, have lupus, heart or kidney disease or are taking heart medications such as digitalis. Additionally, excess vitamin D may aggravate certain diseases, points out Medline Plus, including hyperparathyroidism and kidney disease.


Mineral oil taken internally interferes with the absorption of vitamin D because it is a fat soluble vitamin, according to The PDR Health website reports interactions of high doses of vitamin D with antacids containing aluminum, magnesium supplements, Orlistat (Xenical) and Cholestyramine (Questran).