Levothyroxine

Sounds like 'lee-voe-thy-rox-een'

Key points about levothyroxine

Levothyroxine is a thyroid hormone, used to treat hypothyroidism.
In Aotearoa New Zealand, levothyroxine is available as tablets called Eltroxin®,Synthroid® or Mercury Pharma® brand.
Find out how to take it safely and possible side effects.

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Levothyroxine replaces or provides thyroid hormones when your body can't make enough. This is a condition called hypothyroidism.

Levothyroxine is also used to treat other types of thyroid disorders, such as certain types of goiters and thyroid cancer. Read more about hypothyroidism.

In Aotearoa New Zealand levothyroxine is only available when written on a prescription by a prescriber.

It's available as tablets in different strengths (25 micrograms, 50 micrograms and 100 micrograms) and different brands (eg, Eltroxin®, Synthroid®, Mercury Pharma®).

In Aotearoa New Zealand, there are 3 different brands of levothyroxine tablets – Eltroxin®, Synthroid® and Mercury Pharma®.

These brands are all slightly different from each other and are not interchangeable. It’s important to stay on the same brand.

If your tablets look different from usual, check with your pharmacist to make sure you have the correct brand.

All the brands come in different strengths, and sometimes you may need to take more than one strength (which might be different brands from each other) to make up your dose. If this is the case, you should receive the same brand for each strength you take. Always check that the brands you receive match what you've had before.

Switching between brands should only be done under medical supervision, as even small differences can affect how well your treatment works. If you do have to switch brands of levothyroxine, you’ll have blood tests to check how well the medicine is working for you until the best dose is worked out.

The dose of levothyroxine will be different for different people. It depends on your medical condition, blood test results and your response to treatment.
Your healthcare provider will usually start you on a low dose and increase the dose depending on how you respond.
The usual starting dose for adults is 50 to 100 micrograms daily, which may be increased slowly to 100 to 200 micrograms daily. Lower doses are used for older adults and children.
Levothyroxine is usually taken once a day.
To get your dose correct for your body, you may be told to take doses every second (alternate) days or only on certain days of the week.
Always take your levothyroxine exactly as your healthcare provider has told you. The pharmacy label on your medicine will tell you how much levothyroxine to take, how often to take it and any special instructions
If you have trouble remembering when to take your medicines see tips to help you remember to take your medicines regularly. You might find a medication reminder app helpful.

Timing: Levothyroxine is best taken on an empty stomach. It’s preferable to take it first thing in the morning on an empty stomach – at least 30 minutes to 1 hour before any food, medicines or hot drinks of the day.
Food and drinks with caffeine in them can lower the absorption of levothyroxine so it doesn’t work as well.
Swallow the tablets whole. Don’t cut or chew the tablets. Your pharmacy can make a levothyroxine oral liquid for you if necessary.
Try to take it at the same time each day.
If you keep forgetting to have it on an empty stomach, and you end up missing your medicine, it's better to just take it at the time that suits you best, and your healthcare provider can increase the dose if needed. Talk to your healthcare provider about this.
Other medicines: Taking some medicines (eg, antacids, iron or iodine containing products) at the same time, can reduce the effect of levothyroxine. Don’t take antacids, iron or iodine containing products within 4 hours of taking this medicine.
Missed dose: If you forget to take your dose, take it as soon as you remember. But if it's nearly time for your next dose, just take the next dose at the usual time. Don't take 2 doses to make up for a missed dose.

Blood tests: You'll need blood tests while taking levothyroxine to check how well the medicine is working for you. More frequent blood tests may be needed when you change doses or brands.
Other medicines: Levothyroxine may interact with other some other medicines, herbal supplements and rongoā Māori, so check with your healthcare provider or pharmacist before starting levothyroxine and before starting any new products.
Keep taking levothyroxine regularly: It takes a few weeks before you feel the full effects of levothyroxine. Don't stop taking levothyroxine suddenly, talk to your healthcare provider before stopping. Levothyroxine treatment is usually lifelong.
Pregnancy or breastfeeding: Talk to your healthcare provider if you're pregnant, planning a pregnancy or want to breastfeed.
Different brands: There are different brands of levothyroxine tablets. It's best to continue taking the same brand of tablets. If you have any questions about the brand you're taking, or if your tablets look different to your last supply, ask your healthcare provider or pharmacist for advice.
Different strengths: Levothyroxine tablets are available in different strengths. If your tablets look different to your last supply, ask your healthcare provider or pharmacist for advice.

Like all medicines, levothyroxine can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Side effects	What should I do?
Hair loss	This can happen during the first few months of treatment and should stop once your body gets used to the medicine. It could also happen as a normal part of your hypothyroidism condition. Tell your healthcare provider if this continues or gets worse.
Feeling sick (nausea) Headache	These are common. Tell your healthcare provider if these bother you.
Feeling restless Increased sweating Feeling flushed or hot Feeling nervous or mood swings Diarrhoea (runny poos) Increased appetite Having trouble sleeping	These can happen if your dose isn't right. Tell your healthcare provider so your dose can be adjusted.
Fast or irregular heart beat Chest pain Shortness of breath	Tell your healthcare provider immediately or phone Healthline 0800 611 116.

Signs of an allergic reaction such as skin rash, itching, blisters, peeling skin, swelling of your face, lips or mouth or having problems breathing	This is rare. Stop taking levothyroxine and phone 111 for an ambulance.