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Levothyroxine Sodium

Eltroxin tablets are prescribed for the treatment of thyroid hormone deficiency, also known as hypothyroidism. They contain the functioning agent levothyroxine sodium.

If you are looking to renew your prescription and buy Eltroxin online, you can do so through our pharmacy service. Take our questionnaire to start your consultation.

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PLEASE NOTE: This treatment is not available through our online pharmacy service. This page is for information only. If you are experiencing any of the symptoms related to the condition(s) this medication treats, we strongly recommend that you see your GP in person.

This content was reviewed by a clinician on

26 April 2022
dr daniel

Dr Daniel Atkinson

(GP Clinical Lead - GMC No. 4624794) 26 April 2022
Product information


Eltroxin tablets are marketed in the UK by Advanz Pharma, and are used to supplement hormone deficiency in cases of hypothyroidism. The active ingredient, levothyroxine sodium, replicates the actions of the thyroxine hormone and thereby reduces symptoms associated with an underactive thyroid. You can renew your prescription for Eltroxin online from our UK based pharmacy.

  1. Simple tablet treatment
  2. Available in two strengths
  3. Reduces symptoms of hypothyroidism

Hypothyroidism, which is also referred to as thyroid hormone deficiency, is caused by an underactive thyroid gland, which is situated in the neck. Its function is to secrete hormones that regulate the body’s metabolism, and this helps to control a range of organ functions, muscle growth and digestion. It is different to hyperthyroidism, where the thyroid gland generates too much of the hormone.

You may not notice the symptoms of hypothyroidism for quite some time, as they can be slow to develop, taking several years in some cases. You may have an underactive thyroid gland if you find you have gained a lot of weight, are feeling tired, lethargic, or depressed, are constipated, feel the cold more than you used to, or your muscles are aching.

The cause of an underactive thyroid is normally a disorder called autoimmune thyroiditis, where the thyroid gland is attacked by the immune system, affecting its ability to produce hormones.

If you think you may have hypothyroidism, you should see your doctor, who will refer you for a blood test to determine your hormone levels. If you do have an underactive thyroid gland, you will usually be prescribed hormone replacement tablets. Eltroxin is the branded version of levothyroxine, a commonly prescribed treatment for this condition.

The functioning component of Eltroxin, levothyroxine sodium, works by supplementing the levels of the naturally occurring hormone thyroxine. It can take some time to find the right dosage and for your body to respond to the treatment. Regular blood tests are also required to check your hormone levels.

If you have never taken Eltroxin before or are developing symptoms for the first time, you should see your GP in person. They will need to undertake tests to check your thyroid function before prescribing a treatment.

Patients already taking this medicine can renew their Eltroxin prescription with us. What you’ll need to do is take our confidential medical questionnaire, and one of our doctors will review your case. If approved, a prescription will be sent to our pharmacy, who will dispense and ship your treatment by special next day delivery.

Page last reviewed:  26/04/2022


It is very important that you follow the instructions closely, and adhere to any additional directions given to you by your doctor. This will improve the efficacy of your treatment and help you to avoid side effects.

  1. Use as prescribed.
  2. The tablets should be taken at least half an hour before breakfast or any caffeine based drinks. This will ensure that the medicine is absorbed into your system properly.
  3. Swallow the tablets with water.
  4. Your dosage will be determined by your doctor. The usual starting dose for adults is 50mg or 100mg a day. Your eventual daily dose could be up to 200mg per day.
  5. If you are over 50 or have heart problems, your dosage will normally be lower.
  6.  If you forget to take your tablets, simply take them when you remember, unless it is almost time for your next dose. In this case you should skip that dose and then carry on as normal.
  7. Do not take more than one dose at once to make up for any you have missed.
  8. If you take more Eltroxin tablets than you should, see your doctor immediately or go to your local hospital.
  9. This is a long term course of treatment. Do not stop taking this medicine unless instructed to by your doctor.

These directions are included here as an outline for your guidance. Please read the full set of instructions on the leaflet included with your tablets before starting the course.


Page last reviewed:  26/04/2022
Please read the patient information leaflet for this medicine fully before use:

Eltroxin 50mcg

Eltroxin 25mcg

Eltroxin 100mcg

Side effects & Warnings

Side Effects

It is important to be aware of the possible side effects of any medication before you start taking it.

You must stop taking the tablets and seek immediate medical help if you have any symptoms of an allergic reaction, including: swelling of the face, lips, throat or tongue, difficulties with breathing, sensitivity to sunlight, itchy, red or lumpy skin rashes, pain in the joints, or malaise (a general sense of being unwell). This reaction is rare.

You should also seek urgent medical attention if you have a serious reaction to raised levels of thyroid hormones, known as a ‘thyroid crisis’. Symptoms of this are: jaundice, accelerated heartbeat or arrhythmia, high temperature, feelings of confusion, hypotension (low blood pressure), convulsions, heart failure, or loss of consciousness.

Many of the other side effects are like the symptoms of hyperthyroidism, the condition where the levels of thyroid hormones are too high and as such may be related to your dosage. You doctor may choose to alter your dose if you experience any of the following symptoms: headaches, hot flushes, high temperature, excess sweating, feeling excitable or restless, disturbed sleep, shaking, being sick, diarrhoea, chest pains, loss of weight, cramping or weakness of the muscles, fast or irregular heartbeat, or disturbed menstrual cycles.

This list of side effects is not comprehensive; please consult your leaflet for more detailed instructions about potential side effects.


Regular testing

You will need to have your thyroid function checked regularly (at least once a year) while taking this treatment. See your GP or specialist to arrange this.

Taking it with other medicines

Make sure you tell your doctor about any other prescription or nonprescription medication you are currently using when undergoing consultation.

The following medicines can interfere with the way this medication works: sertraline; anticonvulsants including carbamazepine, primidone, phenytoin and barbiturates; antacid treatments; cholestyramine and colestipol; any medicines taken orally that contain iron; cimetidine or proton pump inhibitors like omeprazole, lansoprazole and pantoprazole; sucralfate; polystyrene sulfonate resin; rifampicin; imatinib; amiodarone; beta blockers including atenolol and sotalol; hormone replacement therapies and oral contraceptives containing oestrogen; male hormone replacement therapies containing androgen; or corticosteroids such as prednisolone and hydrocortisone.

The following medicines can all be affected by the use of Eltroxin: insulin and metformin; blood thinners like warfarin; the family of tricyclic antidepressants, which include imipramine, amitriptyline, and dosulepin; propranolol; anti inflammatory drugs like aspirin or phenylbutazone; adrenaline, phenylephrine or any other medication that stimulates the sympathetic nervous system; or digoxin.

If you are having surgery, inform your doctor you are taking Eltroxin; if ketamine is being used as an anaesthetic this can also be affected.

Conditions to look out for

Disclose your medical history to your doctor during consultation.

You should not take this medicine if you: are allergic to any of the ingredients; have an overactive thyroid gland (hyperthyroidism); or have an illness that affects the function of your adrenal glands.

Your doctor will take special care when prescribing this medicine, or may not recommend it, if you: are over 50; are undergoing treatment for diabetes; have a heart condition such as angina, high blood pressure, or coronary heart disease; or have had an underactive thyroid (hypothyroidism) for a long time.

Pregnancy and breastfeeding

If you are pregnant, breastfeeding, think you could be pregnant or are planning to have a baby you should discuss your medication with your doctor. This is particularly important if you are in the first trimester of your pregnancy.

Driving and machinery

You should be able to drive and operate machinery as normal when taking this medicine, provided you experience no side effects which inhibit your capacity to do so.

Lactose intolerance

Eltroxin contains lactose, therefore if you have an intolerance to some sugars, speak to your doctor before taking this medicine.  

Page last reviewed:  26/04/2022
Please read the patient information leaflet for this medicine fully before use:

Eltroxin 50mcg

Eltroxin 25mcg

Eltroxin 100mcg


Can I still drink alcohol?

This medication is not thought to interact with alcohol.

Will I still be able to drive?

Yes, unless any side effects prevent your ability to do so safely; in this case you should refrain from driving and consult your doctor.

Can I take the medicine while pregnant?

You should speak to your doctor before using this treatment if you are pregnant, become pregnant, are breastfeeding or are thinking of getting pregnant.

How should I store it?

In its original packaging, at room temperature below 25°C, and where it cannot be accessed by children.

Am I allergic to anything in the medicine?

Eltroxin tablets contain: anhydrous levothyroxine sodium, sodium citrate, acacia powder, lactose, magnesium stearate and maize starch.

Let your doctor know if you have an intolerance to lactose.

The oral solution contains: levothyroxine sodium, glycerol, citric acid monohydrate, sodium methyl parahydroxybenzoate (E219), sodium hydroxide and purified water.

If you are allergic to any of the other ingredients you should not take this medicine.

Is it available over-the-counter?

No. A prescription must be obtained to buy Eltroxin online or from a chemist. 

Is it right for me?

Patients who have not used this treatment before or who have not received a diagnosis or hypothyroidism should see their doctor in person. Blood tests and other checks will be necessary before an initial prescription for this medicine can be supplied.

If you are already taking Eltroxin and want to renew your prescription online, our secure service enables you to have your treatment issued and shipped to you. Select your medicine and take our questionnaire. Your answers will be checked by a GMC-registered doctor. Once approved, your e-prescription will be sent to our UK pharmacy to be dispensed.

Page last reviewed:  26/04/2022
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