Liothyronine 20mcg Tablets (T3)
Liothyronine 20mcg tablets contain liothyronine sodium, a synthetic form of triiodothyronine (T3) — the active thyroid hormone. Unlike levothyroxine (T4), which the body must first convert into T3, liothyronine is already in its active form, so it acts more quickly and is cleared from the body faster.
This is a prescription-only medicine (POM). We dispense it against a valid UK private prescription. We do not provide the prescription and we cannot prescribe.
What liothyronine is used for
Liothyronine 20mcg tablets are licensed for the treatment of hypothyroidism (an underactive thyroid), including situations where a rapid response is required. Liothyronine is sometimes prescribed by a specialist alongside or in place of levothyroxine where a patient has not responded adequately to levothyroxine alone.
Why is liothyronine rarely prescribed on the NHS?
NICE guidance on thyroid disease (NG145) advises that liothyronine should not be routinely offered — either alone or in combination with levothyroxine — because there is not enough evidence that it consistently improves outcomes compared with levothyroxine. Where it is prescribed on the NHS, initiation is usually restricted to a consultant endocrinologist. Cost has historically been a further barrier, although UK prices have fallen substantially since 2018.
As a result, many patients access liothyronine through a private endocrinologist or private GP and have the prescription dispensed by a registered pharmacy such as ours.
Dosage
Always take liothyronine exactly as your prescriber has told you. Typical adult dosing begins at 10–20 micrograms daily, adjusted gradually according to response, and is often taken in divided doses across the day because of liothyronine’s short duration of action. Older adults and people with heart conditions are usually started on a lower dose.
As a guide, the BNF states that 20–25 micrograms of liothyronine is broadly equivalent to 100 micrograms of levothyroxine. This is a guide only — your prescriber will determine your dose.
Do not adjust your own dose. Your prescriber will monitor your thyroid function with blood tests.
Who should not take liothyronine
- People with an overactive thyroid (thyrotoxicosis)
- People with untreated adrenal insufficiency
- Anyone allergic to liothyronine sodium or any of the tablet’s other ingredients
Tell your prescriber before taking liothyronine if you have heart disease, angina, high blood pressure, diabetes, or a history of thyroid problems following treatment for an overactive thyroid.
Possible side effects
Most side effects of liothyronine are signs that the dose is too high — effectively the symptoms of an overactive thyroid. These can include:
- Palpitations, or a fast or irregular heartbeat
- Chest pain or angina
- Tremor, restlessness, anxiety or difficulty sleeping
- Sweating, flushing or heat intolerance
- Headache, muscle cramps or muscle weakness
- Diarrhoea, weight loss or increased appetite
Contact your prescriber if you experience any of these. Suspected side effects can be reported via the MHRA Yellow Card scheme at yellowcard.mhra.gov.uk.
Medicines that can interact with liothyronine
- Iron and calcium supplements, antacids and colestyramine — these reduce absorption. Leave at least four hours between them and your liothyronine.
- Warfarin and other anticoagulants — the anticoagulant effect may be increased.
- Insulin and oral diabetes medicines — dose adjustments may be needed.
- Amiodarone, digoxin and some antidepressants — tell your prescriber if you take any of these.
This is not a complete list. Always tell your prescriber and pharmacist about every medicine you take, including anything bought over the counter.
Storage
Store Liothyronine 20mcg tablets below 25°C in the original packaging, protected from light and moisture. Keep out of the sight and reach of children.
How to order
- Liothyronine 20mcg tablets are dispensed only against a valid UK private prescription.
- Your prescription must be dated within the last 28 days. Older prescriptions cannot be processed.
- Send your prescription (paper or electronic) to the pharmacy before or with your order.
- £10 of the price is a non-refundable handling fee covering the checking and validation of your prescription. It is not refunded if your prescription is invalid or your order cannot be fulfilled.
Frequently asked questions
Is liothyronine the same as levothyroxine?
No. Levothyroxine is T4, which your body converts into the active hormone T3. Liothyronine is T3 — already active. It works faster but has a much shorter duration of action, which is why it is often taken in divided doses.
Can I buy liothyronine without a prescription in the UK?
No. Liothyronine is a prescription-only medicine. Any website offering it without a prescription is operating illegally, and the product cannot be assumed to be genuine.
Do you provide the prescription?
No. We are a dispensing pharmacy, not a prescribing service. You will need a private prescription from a UK-registered prescriber, usually an endocrinologist or private GP.
How will my thyroid levels be monitored?
Your prescriber will arrange blood tests. TSH is often suppressed on liothyronine, so free T3 and free T4 are usually more informative. Monitoring is typically every three to six months once you are stable.
Which brand will I receive?
Brands may vary depending on wholesaler availability. If you need a specific manufacturer, please contact us before ordering.
Do you dispense other thyroid medicines?
Yes. Please contact us if you hold a private prescription for another thyroid medicine.
Is this the same as “T3” sold for weight loss or bodybuilding?
Liothyronine is licensed for the treatment of hypothyroidism. It is not licensed, and should not be used, for weight loss or physique enhancement. We dispense only against a valid private prescription written for a legitimate clinical indication.
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