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  • Alfacalcidol is a type of vitamin D.
  • You will need to have regular blood tests while you are taking this medicine so that your doctor can make sure the dose is right for you.
  • Make sure you know the symptoms of too much calcium in your blood - these are losing your appetite, feeling thirsty, being sick, feeling tired, and losing weight. See your doctor if you develop these symptoms.
Type of medicineVitamin D supplement
Used forTo promote healthy bones
Also calledOne-Alpha®
1α-hydroxyvitamin D3
Available asCapsules, oral drops and injection

Vitamin D is important for healthy, strong bones. Alfacalcidol is a type of vitamin D. A mild lack of vitamin D may not cause any symptoms, but can cause general aches and pains. A more severe lack can cause serious problems such as rickets in children and osteomalacia in adults. If you are at risk of vitamin D deficiency, you will be recommended to take a vitamin D supplement such as alfacalcidol routinely. Most vitamin D supplements need 'activating' by the kidneys. Alfacalcidol is a form of vitamin D which does not need this activation process, and so it is particularly helpful in people who have kidney problems.

Alfacalcidol will help your body absorb the calcium that you eat or drink in your diet, and this will help strengthen your bones.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking alfacalcidol it is important that your doctor or pharmacist knows:

  • If you are pregnant or breast-feeding.
  • If you have ever been told you have high levels of calcium in your blood.
  • If you have kidney stones.
  • If you are taking other medicines, including those available to buy without a prescription, herbal and complementary medicines.
  • If you have ever had an allergic reaction to this or to any other medicine.
  • Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack. The leaflet will give you more information about alfacalcidol, and a full list of possible side-effects from taking it.
  • Take alfacalcidol exactly as your doctor has told you. Your doctor or pharmacist will tell you how much to take each day. Your dose will also be on the label of the pack.
  • If you have been given capsules, take them with a drink of water.
  • Try to take your doses at the same times each day as this will help you to remember to take them.
  • If you forget to take a dose, take it as soon as you remember. If you do not remember until the following day, skip the missed dose. Do not take two doses together to make up for a forgotten dose.

Instructions for using alfacalcidol drops:

  • Do not shake the bottle before measuring out a dose.
  • Remove the bottle cap. You will see a dropper which is ready for you to use.
  • Hold the bottle upside down so that a drop appears at the end of the dropper.
  • Let the drop fall into your (or your child's) mouth, or catch it on a spoon if this is easier.
  • Your doctor will have told you how many drops to take - count these out carefully to make sure you take the correct dose.
  • Try to keep your regular appointments with your doctor. This is so your doctor can check on your progress. Also, your doctor will want to do some blood tests during this treatment to check your levels of calcium to make sure the dose is right for you.
  • If you buy any medicines, check with a pharmacist that they are suitable to take with alfacalcidol.
  • Treatment with alfacalcidol is usually long-term unless you experience an adverse effect. Continue to take the alfacalcidol unless you are advised otherwise by your doctor.
  • If you are having an operation or dental treatment, tell the person carrying out the treatment that you are taking alfacalcidol.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Possible alfacalcidol side-effects What can I do if I experience this?
Skin rash and itchinessIf troublesome, speak with your doctor
Loss of appetite, loss of weight, feeling sick, feeling thirsty, sweating, a metallic taste in your mouth, a need to pass urine more oftenThese are signs that there may be too much calcium in your blood. Make an appointment to see your doctor staightaway

If you experience any other symptoms which you think may be due to alfacalcidol, discuss them with your doctor or pharmacist.

  • Keep all medicines out of the reach and sight of children.
  • If you have been prescribed capsules, store these in a cool, dry place, away from direct heat and light.
  • If you have been prescribed drops, keep these refrigerated. Once the bottle has been opened, you should not use it for longer than 28 days. After this time, make sure you have a fresh supply.
  • Never take more than the prescribed dose. If you suspect that you or someone else has taken an overdose of this medicine, go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.
  • This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
  • Never keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
  • If you have any questions about this medicine ask your pharmacist.

Further reading & references

  • British National Formulary; 63rd Edition (Mar 2012) British Medical Association and Royal Pharmaceutical Society of Great Britain, London
  • Manufacturer's PIL, One-Alpha® Capsules; Manufacturer's PIL, One-Alpha® Capsules, Leo Laboratories Limited, The electronic Medicines Compendium. Dated February 2009.
  • Manufacturer's PIL, One-Alpha® Drops,; Manufacturer's PIL, One-Alpha® Drops, Leo Laboratories Limited, The electronic Medicines Compendium. Dated December 2011.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Document ID:
3404 (v23)
Last Checked:
Next Review:
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