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What does it do?

Levothyroxine is a thyroid hormone. It is used if your thyroid gland does not make enough thyroid hormone.

Before you start

  • Tell your doctor if you are pregnant, planning to become pregnant, or breastfeeding.

How should you take it?

Take levothyroxine regularly as directed with a glass of water.

What if you forget a dose?

Take the missed dose as soon as possible and continue as directed.

Can you take other medicines?

Some medicines available without a prescription may react with levothyroxine including:

  • products containing aluminium, calcium, iron or magnesium, such as antacids (e.g. Mylanta®) or multivitamins

Tell your pharmacist or doctor about all medicines or treatments that you may be taking, including vitamins, herbal products or recreational drugs.

What side effects might you notice?

Side EffectsRecommended action

Symptoms of a fast or irregular heartbeat including: fluttering, pounding or pain in your chest, dizziness or fainting

Feeling hotter than normal, sweating

Nervousness, restlessness, tremor, trouble sleeping

Diarrhoea, weight loss

Hair loss or thinning

Changes in periods

Tell your doctor - they may need to change your dose.

If you notice any other effects, discuss them with your doctor or pharmacist.

Other information:

  • You will need regular blood tests while you are taking levothyroxine to make sure you are on the right dose.
  • Levothyroxine should not be used for weight loss.

This leaflet contains important, but not all, information about this medicine.

Prepared by the MyMedicines Committee at Christchurch Hospital, Te Whatu Ora - Waitaha, New Zealand. March 2023

For more general information about this sheet and its contents, see: What does a My Medicines sheet cover?

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About My Medicines

My Medicines Patient Information Leaflets (PILs) contain important, but not all, information about the medicines they describe.

For more information about the sheets, see: What does a My Medicines sheet cover?

My Medicines is developed by a team at Te Whatu Ora – Waitaha. Our team is made up of doctors, pharmacists, and a non-medical person to help us keep to plain language. We also discuss our information with specialist health professionals or groups when needed