Colecalciferol
Also known as: Vitamin D3, Fultium, InVita D3
What it's for
Colecalciferol is vitamin D. It helps your body absorb calcium for strong bones. It treats and prevents vitamin D deficiency, which is common in the UK due to limited sunlight.
Comes as: Capsules, tablets, or drops
How to take it
- For maintenance: Usually 400 to 1000 units (10-25 micrograms) daily.
- For deficiency: Higher doses as prescribed by your doctor.
- Take with or without food.
- Some preparations are taken weekly or monthly.
Doses here are typical. Always follow the instructions from your prescriber or on the packet — they come first.
Common side effects
- Side effects are rare at recommended doses
- Too much vitamin D: feeling sick, weakness, or kidney problems
The leaflet inside the packet lists all known side effects.
Important safety points
- Do not take more than recommended - too much can be harmful
- Tell your doctor if you have kidney problems or high calcium
- Some medical conditions affect how you use vitamin D
Get medical help urgently if…
- You have severe nausea, vomiting, or weakness
- You are very thirsty and passing lots of urine
- You have confusion or feel very unwell
Call NHS 111 for urgent advice, or 999 if someone is seriously unwell.
Before you act on anything here
This page is general information, written to help you understand — it is not personal medical advice and it cannot tell you what is right for you. Talk to your own GP, pharmacist or nurse about your own health.
- Need help now but it's not an emergency? Call NHS 111 or use 111.nhs.uk.
- Emergency? Call 999 or go to A&E.