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Dihydrotachysterol

vitamin D

Clinical author's note Michael Stewart 05/12/2022: AT10® oral drops were discontinued in the United Kingdom in January 2021. At the time of review there are no branded or generic products containing dihydrotachysterol available in the UK. Dihydrotachysterol may still be available in other countries. Other forms of vitamin D are available. This medicine leaflet is based on medical information available in the UK at the time of writing and is left here for reference purposes. Please also refer to the manufacturer's information supplied with your medicine.

Dihydrotachysterol is a type of vitamin D. It helps your body absorb calcium.

Make sure you understand how much to take and when to take it.

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 (vomiting), feeling tired, and losing weight. See your doctor if you develop these symptoms.

At a glance

  • Dihydrotachysterol is a form of vitamin D used to treat low blood calcium caused by hypoparathyroidism.

  • Take this medicine exactly as your doctor tells you, using the dropper for measuring.

  • If you are allergic to peanuts or soya, you must not take this medicine.

  • You will need regular blood tests to ensure your dose is correct.

  • Signs of too much calcium, like tiredness or feeling sick, mean your dose may need adjusting.

  • If you experience symptoms of too much calcium, see your doctor straightaway.

Continue reading below

About dihydrotachysterol

Type of medicine

A type of vitamin D

Used for

Low blood calcium levels due to hypoparathyroidism

Also called

AT10® (discontinued)

Available as

Oral solution (drops)

Dihydrotachysterol is a form of vitamin D. Vitamin D helps you to absorb calcium from the foods you eat. You need calcium to keep your bones strong, and to help your muscles and nerves work properly. If you have a low level of calcium in your blood, it can cause a number of different symptoms, including muscle cramps, pain and twitching. Low levels of calcium can be caused by a problem with your parathyroid glands, called hypoparathyroidism. Dihydrotachysterol is used to treat low blood levels of calcium when caused by hypoparathyroidism.

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 dihydrotachysterol it is important that your doctor knows:

  • If you are allergic to peanuts or soya. If so, you must not take this medicine.

  • If you are pregnant or breastfeeding.

  • If you have sarcoidosis. This is a condition causing inflammation, particularly in your lungs and lymph system. Sarcoidosis may make you more sensitive to dihydrotachysterol than normal.

  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.

  • If you have ever had an allergic reaction to a medicine.

Continue reading below

  • Before you start this treatment, read the manufacturer's printed information leaflet from inside your pack. The leaflet will give you more information about dihydrotachysterol and a full list of side-effects which you may experience from taking it.

  • Take dihydrotachysterol exactly as your doctor tells you to. It is likely you will be asked to take 3-5 ml for the first three days, and then your dose will be adjusted depending on the results of a blood test. You could then be asked to take a dose each day, on alternate days, or several times a week. Your doctor will tell you what is right for you, and how much to take for each of your doses.

  • Make sure you understand how to measure out your doses using the dropper. You can ask your doctor, nurse or pharmacist to explain this to you again if you are uncertain.

  • You can take dihydrotachysterol before or after meals.

  • If you forget to take a dose, take it as soon as you remember unless it is nearly time for your next dose, in which case leave out the missed dose. Do not take two doses together to make up for a forgotten dose.

  • Keep your regular doctor's appointments so your progress can be monitored. You will need to have regular blood tests while you are taking this medicine to make sure that the dose you are taking is correct for you.

  • You should consider wearing a MedicAlert® bracelet (or similar), or carry some kind of ID with you, to identify yourself as having hypoparathyroidism. This is so that if you collapse, are confused or are injured, doctors will know that you need prompt treatment with calcium.

  • Eating foods rich in vitamin D and calcium may help, such as oily fish (sardine, herring, salmon and tuna), liver, dairy products and eggs.

  • If you buy any medicines, check with a pharmacist that they are suitable for you to take with dihydrotachysterol.

  • Treatment with dihydrotachysterol is usually long-term. Continue to take it regularly 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 dihydrotachysterol.

Continue reading below

Along with their useful effects, medicines can cause unwanted side-effects although not everyone experiences them. Any side-effects caused by dihydrotachysterol are likely to be due to too much calcium in your blood, which means that your dose will need adjusting.

The first signs of too much calcium are:

  • Loss of appetite.

  • Tiredness.

  • Feeling sick (nausea).

This could then lead on to:

  • Being sick (vomiting).

  • Stomach cramps.

  • Feeling thirsty.

  • Needing to pass urine more often.

  • Sweating.

  • Dizziness.

  • Headache.

If you experience these symptoms, it is important that you make an appointment to see your doctor straightaway.

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

  • Keep the bottle tightly closed and store in the original carton to protect it from light.

  • Discard any remaining contents four months after first opening the bottle. Write the date of opening on the label to remind you.

Important information about all medicines

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. 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.

Do not 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.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

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Unsure about mixing medicines?

Check for possible interactions between medicines, supplements and foods before taking them together.

Frequently asked questions

What is hypoparathyroidism?

Hypoparathyroidism is a condition where low levels of calcium in the blood are caused by a problem with your parathyroid glands. Dihydrotachysterol is specifically used to treat low blood calcium when it is due to this condition.

How will my doctor determine the correct dose of dihydrotachysterol for me?

Initially, you will likely be prescribed 3-5 ml for the first three days. After this, your doctor will adjust your dose based on the results of blood tests. The frequency of doses, whether daily, on alternate days, or several times a week, will also be determined by your doctor to suit your individual needs.

Can I take other supplements or medicines with dihydrotachysterol?

If you buy any over-the-counter or herbal medicines, you should check with a pharmacist to ensure they are safe to take alongside dihydrotachysterol. It's important to inform your doctor about all medicines you are taking, including those without a prescription.

What should I do if I think I've taken too much dihydrotachysterol?

If you suspect that you or someone else has taken more than the prescribed dose of dihydrotachysterol, you should go to the accident and emergency department of your local hospital immediately. Remember to take the medicine container with you, even if it's empty.

How long will I need to take dihydrotachysterol?

Treatment with dihydrotachysterol is usually long-term. You should continue to take it regularly unless your doctor advises you otherwise.

Further reading and references

Continue reading below

About the authorView full bio

Author image

Michael Stewart, MRPharmS

Medicine Leaflet Review Manager – Contractor, Pharmacist

BPharm (Hons), MRPharmS

Michael is a community pharmacist practicing in the Midlands and South Yorkshire with more than 20 years’ experience advising on medicines and medical conditions. He has a strong background in healthcare training, having produced and delivered training courses for pharmacy teams and staff of residential care settings, including nurses. He has also contributed to pharmacy advisory boards for the management of low acuity conditions in the community.

About the reviewer

Author image

Sid Dajani

Sultan Dajani qualified at the London School of Pharmacy in 1994 and became the youngest elected member of the Royal Pharmaceutical Society council since its founding in 1842.

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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