Indications
Vitamin D (most often as cholecalciferol, vitamin D3) is used to prevent and treat vitamin D deficiency and the bone problems it causes, such as rickets in children and osteomalacia (soft bones) in adults. It is often combined with calcium to help prevent and treat osteoporosis (thinning bones), and is used in people with low sun exposure, dark skin, older age, obesity or conditions that reduce absorption.
How It Works
Vitamin D is changed in the liver and then the kidneys into its active form, calcitriol. Calcitriol helps the gut absorb calcium and phosphate from food and helps keep normal blood calcium levels, which are needed for strong bones and teeth and for healthy muscles and nerves. It also supports normal immune function.
Dosage and Administration
For general prevention, adults usually take 400 to 1,000 IU (10 to 25 micrograms) a day, or as directed on the label. Treatment of a confirmed deficiency uses higher daily or weekly doses for a limited time, only as prescribed, often followed by a maintenance dose. Children’s doses depend on age. Take with a meal containing some fat for better absorption.
Interactions
Thiazide diuretics (such as Hydrochlorothiazide) with vitamin D and calcium can raise blood calcium. High calcium levels increase the risk of side effects with Digoxin. Orlistat, Cholestyramine, mineral oil, Phenytoin, Carbamazepine, Phenobarbital and Rifampicin can reduce vitamin D levels. Steroids reduce its effect.
Contraindications
Do not use if you have high blood calcium, high vitamin D levels, calcium-containing kidney stones or severe kidney disease (unless prescribed by a specialist), or if you are allergic to any ingredient.
Side Effects
At normal doses, side effects are rare. Too much over time can raise blood calcium, causing nausea, vomiting, constipation, loss of appetite, thirst, passing a lot of urine, weakness, confusion and kidney stones.
Get urgent medical help if you have severe vomiting, confusion, extreme thirst, irregular heartbeat, severe weakness, or signs of a serious allergic reaction such as swelling of the face or difficulty breathing.
Pregnancy and Lactation
Vitamin D is important in pregnancy and breastfeeding; usual supplement doses (often 400 to 600 IU a day) are recommended. Do not take high doses unless your doctor prescribes them. Breastfed babies may need their own vitamin D drops as advised by a doctor.
Precautions and Warnings
Check all supplements and fortified foods so you do not take too much vitamin D. Use with caution in kidney disease, sarcoidosis and other conditions that raise calcium. Long-term high doses need blood calcium and vitamin D checks.
Overdose
Overdose leads to high blood calcium with nausea, vomiting, confusion, thirst, heart rhythm problems and kidney damage. Stop taking it and seek medical help, especially if a child has swallowed a large amount.
Therapeutic Class
Vitamin (fat-soluble vitamin D).
Storage
Store below 30°C in a dry place, away from light and out of the reach of children.
Prepared by the Oshud Alo team from standard drug references. For information only; always follow your doctor's advice.