Patient Leaflet Updated 12-Mar-2026 | Neon Healthcare Ltd
One-Alpha Drops
One-Alpha® Drops
alfacalcidol
1. What One-Alpha® is and what it is used for
2. What you need to know before you take One-Alpha®
3. How to take One-Alpha®
4. Possible side effects
5. How to store One-Alpha®
6. Contents of the pack and other information
One-Alpha contains the active substance alfacalcidol. One-Alpha belongs to a group of medicines called vitamin D analogues. It is a type of vitamin D.
Vitamin D controls the levels of two substances in your body. These substances are called calcium and phosphate. Your body needs both of these substances for healthy bones and teeth.
One-Alpha works by increasing the amount of vitamin D in your body. This means the levels of calcium and phosphate in your body will increase too.
One-Alpha is used to treat diseases where the amount of calcium in your body needs changing. It is used to treat:
If you are unsure if any of the above apply to you, talk to your doctor before taking One-Alpha.
Talk to your doctor, pharmacist or nurse before taking One-Alpha:
You may get too much calcium or phosphate in your blood when you take this medicine. Please read section 4 of this leaflet so you can spot any signs this may be happening to you. Your doctor may need to change your dose.
While you are taking One-Alpha your doctor will take regular blood tests. This is very important in children, patients with kidney problems, or patients on a high dose of medicine. This is to check the level of calcium and phosphate in your blood while you take your medicine.
Your doctor may prescribe another medicine called a phosphate binding agent to take as well as One-Alpha. This will help to keep the right amount of phosphate in your blood.
Your doctor may also prescribe a calcium supplement to take as well as One-Alpha. This is to maintain the right amount of calcium in your blood.
Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines. This includes any medicines which you have bought without a prescription.
You must tell your doctor or pharmacist if you are taking any of the following medicines:
If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine.
Usually your medicine may have very little effect on your ability to drive or use machines. Check with your doctor if you feel any side effect, for example dizziness, that may stop you from driving or using machines.
One-Alpha contains:
Please ask your doctor if you are worried about any of the ingredients in this medicine.
Always take this medicine exactly as your doctor or pharmacist has told you. Check with your doctor or pharmacist if you are not sure.
Do not shake the bottle. Unscrew the bottle cap. You will see a dropper in the top of the bottle. It is ready to use. Hold the bottle upside down. A drop will form at the end of the dropper. Let the drop fall directly into your mouth. You can catch the drop on a spoon if this is easier.
If the drops do not come out of the bottle straight away, tap the bottle gently until a drop forms.
Your doctor will tell you how many drops to take, or to give your child.
One-Alpha is only to be taken by mouth.
Be careful not to take more drops than you should. You must check with the doctor or pharmacist if you are not sure how to take this medicine correctly. This medicine is very strong (concentrated).
At first you will have weekly blood tests to check the levels of some substances in your blood. These tests are to check the levels of calcium, an enzyme called alkaline phosphatase or the parathyroid hormone. This is so your doctor knows that you are taking the dose that is right for you. When you are getting the correct dose you will not need blood tests so often.
You may also have other tests such as X-rays. This is also so your doctor knows that the dose is right for you.
Your doctor may adjust your dose. Your doctor may ask you to take more or less drops depending on your test results.
You may get too much calcium or phosphate in your blood when you take this medicine. Please read section 4 of this leaflet so you can spot any signs this may be happening to you. Your doctor will tell you not to take any more medicine. You will need to have some blood tests. When the blood tests are normal you can start your medicine again. It is important that you only take half the dose you had before.
Adults and children weighing more than 20 kilograms:
The usual starting dose is 10 drops each day. People usually take between 10 and 30 drops each day.
Most people take between 3 and 10 drops each day once the blood test results show the medicine is working.
If you have very low levels of calcium in your blood, the doctor may prescribe between 30 to 50 drops each day. Your doctor may prescribe another medicine called a calcium supplement to take as well as One-Alpha. This will help to keep the right amount of calcium in your blood.
Elderly:
The usual starting dose is 5 drops each day.
Children:
The dose depends on the weight of the child (called bodyweight).
Tell your doctor straight away. You may need to stop taking this medicine.
You may get too much calcium or phosphate in your blood. Please read section 4 of this leaflet so you can spot any signs this may be happening to you.
If you forget to take your medicine take it as soon as you remember. Then take the next dose at the usual time.
If you have any further questions on the use of this medicine, ask your doctor, pharmacist or nurse.
Like all medicines, this medicine can cause side effects, although not everybody gets them.
You must get urgent medical help if you have any of the following symptoms. You may be having an allergic reaction:
You should tell your doctor straight away if you spot any of the following signs which may be due to too much calcium or phosphate in your blood. These side effects may affect up to 1 in 10 people:
You should tell your doctor as soon as possible if you spot any of the following signs which may be due to problems developing with your kidneys. The frequency of these side effects is not known (cannot be estimated from the available data):
Kidney stones may be forming. Kidney stones may cause a sharp spasm in one side of your lower back.
Other possible side effects which may affect up to 1 in 10 people are:
Uncommon possible side effects which may affect up to 1 in 100 people are:
Rare possible side effects which may affect up to 1 in 1,000 people are:
Side effects with unknown frequency (cannot be estimated from the available data):
If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.
Do not throw away any medicines via waste water or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help protect the environment.
You can find important information about some of the ingredients in your medicine near the end of section 2 of this leaflet.
One-Alpha is a solution of oral drops. One-Alpha is a slightly hazy or clear colourless solution.
One-Alpha comes in an amber glass bottle containing 10 or 20 ml.
Not all pack sizes may be marketed.
Marketing Authorisation Holder:
Manufacturer:
This leaflet was last revised in February 2026.
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+44 (0)1992 926 330
+44 (0)1992 926 330
+44 (0)1992 926 330