Colecalciferol comes in different strengths.
A loading dose is a high strength course of vitamin D treatment that is usually taken for a short time (usually, a few weeks). It is prescribed to raise low levels of vitamin D quickly.
Lower doses of colecalciferol are usually taken to maintain your vitamin D levels or prevent you from getting vitamin D deficiency.
Dosage and strength
Colecalciferol doses are measured in international units (IU). 1 microgram of vitamin D is the same as 40IU.
Adult loading doses
If you have severe vitamin D deficiency, your doctor may prescribe a loading dose of up to 300,000IU. This can be taken as:
- 50,000IU once a week for 6 weeks
- 40,000IU once a week for 7 weeks
- 1,000IU four times a day for 10 weeks
- 800IU five times a day for 10 weeks
Maintenance dose
If you've had a loading dose but need to maintain your vitamin D levels, your doctor may prescribe a maintenance dose of 800IU to 2,000IU a day.
Lower colecalciferol doses
Colecalciferol is also available in lower doses. You can take 400IU a day if you're an adult maintaining your vitamin D levels.
Doses for children
Your child's dose will depend on their age and how severe their vitamin D deficiency is.
The usual loading dose for children is:
- age 1 to 5 months – 3,000IU daily for 8 to 12 weeks
- age 6 months to 11 years – 6,000IU daily for 8 to 12 weeks
- age 12 to 17 years – 10,000IU daily for 8 to 12 weeks
Maintenance dose for children
Your child's doctor may recommend changes to your child's diet to improve their vitamin D levels. If changes to their diet still do not provide enough vitamin D then the doctor may prescribe a maintenance dose of 400IU to 600IU for them to take daily long term.
Prevention doses for children
To help your child grow healthy bones and prevent rickets, you can give them:
- 340IU to 400IU a day – from birth to 1 year
- 400IU a day – from 1 year to 4 years
How to take it
If you're unsure how to take colecalciferol, ask your doctor or your pharmacist. Take your medicine exactly as they advise you to.
Capsules and tablets
If you're taking colecalciferol capsules or tablets, swallow them whole with some water. Take them with your main meal of the day.
Chewable tablets
If you're taking chewable tablets, chew them. Do not swallow them whole.
Syrup (oral solution)
Your colecalciferol liquid should come with a plastic syringe. If you do not have one, ask your pharmacist for one.
Follow the instructions included with your medicine about how to take the syrup with a syringe.
- Measure the amount prescribed by your doctor into the syringe.
- Squirt the medicine straight into your mouth until the syringe is empty.
- Wash the syringe and allow to dry.
Colecalciferol oral drops
If you're using colecalciferol drops, you can either drop them straight into your mouth or onto a spoon before you take it.
Colecalciferol dissolvable tablets
Drop 1 tablet into a glass of water and as soon as it dissolves drink straight away. Do not chew or swallow the tablets whole.
How long to take it for
For adults, if you're taking a loading dose for severe vitamin D deficiency you'll usually take it daily or weekly for 6 to 10 weeks.
To maintain your vitamin D levels or prevent deficiency you'll usually take colecalciferol long term.
Children with severe vitamin D deficiency usually take a loading dose for 8 to 12 weeks. They may then take a lower, maintenance dose of vitamin D long term.
If you or your child's vitamin D levels are OK, your doctor may recommend safely increasing your exposure to sunlight and adding more foods that are high in vitamin D to your diet.
If you stop taking colecalciferol, your symptoms may come back and your bone health may be affected. Stopping colecalciferol could cause the calcium levels in your body to fall. This can cause problems like bone pain or muscle weakness.
If you forget to take it
If you forget to take your daily or weekly dose of colecalciferol, take it as soon as you remember, unless it's nearly time for your next dose. In this case, leave out the missed dose and take your next dose at the usual time.
Never take 2 doses at the same time and do not take an extra dose to make up for a forgotten one.
If you forget doses often, it may help to set an alarm or make a note in your diary to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.
If you take too much
Unless you're taking a loading dose of vitamin D, as prescribed by your doctor, taking an extra dose is unlikely to harm you.
Urgent advice: Contact 111 for advice now if:
- you have taken more than 4,000IU of colecalciferol in 1 day
- your child is between 1 and 10 years of age and has had more than 2,000IU in 1 day
- your child is under 12 months and has had more than 1,000IU in 1 day
Go to 111.nhs.uk or call 111. Call 111 if you are asking about a child under the age of 5 years.
If you need to go to A&E, do not drive yourself. Get someone else to drive you or call for an ambulance.
Take the colecalciferol packet, or the leaflet inside it, plus any remaining medicine with you.
If you have taken too much colecalciferol, tell your doctor or contact 111 straight away if you (or your child):
- feel weak or have pain in your muscles or bones
- need to pee more often
- feel thirsty
- feel tired
- are sick (vomit) or feel sick
- have constipation, or lose your appetite
- are sweating a lot
- have headaches
- feel confused
- feel drowsy
- feel pain in the abdomen – this could be a sign of kidney stones