Can I take Colecalciferol and Levothyroxine together?

Why this happens

There is no direct evidence that Vitamin D stops levothyroxine from being absorbed. However, Vitamin D helps the body absorb calcium. If calcium levels in the blood become very high (hypercalcaemia), it can theoretically alter thyroid hormone sensitivity or metabolism. Additionally, if you take Vitamin D as part of a combined calcium supplement, the calcium itself will block the absorption of levothyroxine.

What you should do

You can take these two medications together. To be safe, it is best to take levothyroxine on an empty stomach, at least 30 to 60 minutes before breakfast or any other medications. If your Vitamin D supplement also contains calcium, you must wait at least 4 hours after taking your levothyroxine before taking the supplement. Your doctor will monitor your thyroid levels (TSH) as part of your routine care.

Important precautions

Hypercalcaemia (high blood calcium)

Do not take colecalciferol if you have high levels of calcium in your blood or urine, or if you have severe kidney stones, as vitamin D increases calcium absorption and can worsen these conditions.

Timing of other medications and supplements

Do not take calcium supplements, iron tablets, or antacids at the same time as levothyroxine. These must be spaced at least 4 hours apart, otherwise the levothyroxine will not be absorbed properly.

Heart disease (e.g. angina, heart failure, or history of heart attack)

Levothyroxine increases the workload on your heart. If you experience chest pain, palpitations, or worsening shortness of breath, you must contact your doctor immediately as your dose may need adjusting.

Diabetes

Levothyroxine can raise blood sugar levels. If you have diabetes, you must monitor your blood glucose more closely when starting or changing your dose, as your diabetes medication may need to be increased.

Food and drink warnings

Alcohol

It is best to avoid or strictly limit alcohol while taking colecalciferol. Long-term heavy alcohol use can interfere with how your body absorbs and processes Vitamin D, making the treatment less effective.

It is best to avoid or strictly limit alcohol while taking levothyroxine. While there is no direct chemical reaction, alcohol can affect thyroid function and may worsen symptoms like tiredness or mood changes.

Caffeine (Coffee/Tea)

Coffee and tea can significantly reduce the amount of levothyroxine your body absorbs. You should wait at least 30 to 60 minutes after taking your tablet before drinking coffee or tea.

Dairy products (Milk/Yoghurt)

Calcium found in dairy products can interfere with the absorption of levothyroxine. Avoid eating or drinking dairy products for at least 30 to 60 minutes after taking your medication.

Soya products

Soya can stop levothyroxine from being absorbed properly. If you eat a diet high in soya, you may need a different dose of levothyroxine. Consult your doctor before making major changes to your soya intake.

Papaya

Some evidence suggests that eating large amounts of papaya may reduce the absorption of levothyroxine.

High-fibre foods

A diet very high in fibre (such as bran) can reduce the absorption of levothyroxine. Try to keep your fibre intake consistent and discuss any major dietary changes with your doctor.

High-fat meals

Colecalciferol is a fat-soluble vitamin. It is best absorbed by your body when taken with a meal that contains some fat (such as eggs, avocado, nuts, or dairy).

Using other medicines

Taking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.

Disclaimer

This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.