UK Edition. Click here for US version.
LEVOTHYROXINE 100MICROGRAMS TABLETS (THYROXINE 100MCG TABS)
Active substance(s): LEVOTHYROXINE SODIUM ANHYDROUS
Levothyroxine 50 and 100 micrograms Tablets
Read all of this leaflet carefully before you start taking this
medicine because it contains important information for you.
- Keep this leaflet. You may need to read it again.
- If you have any further questions, ask your doctor, pharmacist or
- This medicine has been prescribed for you only. Do not pass it on
to others. It may harm them, even if their signs of illness are the
same as yours.
- If you get any side effects, talk to your doctor, pharmacist or
nurse. This includes any possible side effects not listed in this
leaflet. See section 4.
Your medicine is called either Levothyroxine 50 micrograms or 100
micrograms tablets depending on what your doctor has prescribed.
It will be known as Levothyroxine Tablets for ease hereafter.
What is in this leaflet
1. What Levothyroxine Tablets are and what they are used for
2. What you need to know before you take Levothyroxine Tablets
3. How to take Levothyroxine Tablets
4. Possible side effects
5. How to store Levothyroxine Tablets
6. Contents of the pack and other information
1. WHAT LEVOTHYROXINE TABLETS ARE AND
WHAT THEY ARE USED FOR
Thyroxine is a hormone which is produced naturally in the body by
the thyroid gland. Levothyroxine is a synthetic version of this
hormone. Thyroxine controls how much energy your body uses.
When the thyroid gland does not produce enough thyroxine (a
condition known as hypothyroidism), many of the body’s functions
slow down. Some of the most common symptoms of hypothyroidism
• weight gain
• feeling depressed
Levothyroxine tablets are used to replace the thyroxine that your
thyroid gland cannot produce and prevent the symptoms of
hypothyroidism. Before starting your treatment your doctor will carry
out a blood test to work out how much levothyroxine you need.
2. WHAT YOU NEED TO KNOW BEFORE YOU
TAKE LEVOTHYROXINE TABLETS
Do not take Levothyroxine tablets
• if you are allergic to levothyroxine or any of the other ingredients
of this medicine (listed in section 6)
• if you suffer from an overactive thyroid gland that produces too
much thyroid hormone (thyrotoxicosis)
• if you have any condition that affects your adrenal glands (your
doctor will be able to advise you if you are not sure).
If any of these apply to you, do not take this medicine and go back to
your doctor to discuss your treatment.
Warnings and precautions
Talk to your doctor, pharmacist or nurse before taking
• if you have suffered with an under active thyroid gland for a long
• if you suffer from heart problems including angina, coronary
artery disease or high blood pressure
• if you are being treated for diabetes. The dose of your antidiabetic medicine may need to be changed as levothyroxine can
raise blood sugar levels
• if you are over 50 years of age.
Before you start taking levothyroxine your doctor will do a blood test
to see how much thyroxine your thyroid gland is making and what
dose of the medicine you will need. Once you start taking
the medicine your doctor will want you to have regular blood tests to
see how well the medicine is working.
Other medicines: and levothyroxine tablets
Tell your doctor or pharmacist if you are taking, have recently taken
or might take any other medicines. This includes over the counter
medicines, herbal remedies and vitamin supplements. Many
medicines affect the way levothyroxine works. The effects of other
drugs may also be affected by levothyroxine.
The following may affect the way that levothyroxine works:
• medicines for epilepsy such as carbamazepine, phenytoin,
primidone and barbiturates
• sertraline – used to treat depression and anxiety disorders
• antacids – used to treat indigestion
• medicines containing calcium salts
• cimetidine – used to reduce excess stomach acid
• proton pump inhibitors such as omeprazole, lansoprazole and
pantoprazole - used to reduce the amount of acid produced by
• sucralfate – used to treat and prevent stomach and duodenal
• cholestyramine and colestipol – used to treat high level of fat in
• polystyrene sulphone resin – used to reduce high levels of
potassium in the blood
• medicines containing iron that are taken by mouth
• rifampicin – used to treat infections
• imatinib – used to treat certain types of cancer
• beta blockers such as atenolol and sotalol – used to treat high
blood pressure and heart problems
• oestrogen containing medicines for hormone replacement
therapy (HRT) and contraception (the ‘pill’)
• androgen containing medicines for male hormone replacement
• corticosteroids such as hydrocortisone and prednisolone –
used to treat inflammation
• amiodarone – used to treat an irregular heart beat
• orlistat – used to treat obesity.
The following may be affected by levothyroxine:
• anticoagulant medicines to prevent blood clots such as warfarin
• medicines to treat diabetes such as insulin and metformin
• tricyclic antidepressants such as amitriptyline, imipramine and
• medicines that stimulate the sympathetic nervous system such as
adrenaline (used to treat severe allergic reactions) or
phenylephrine (a decongestant found in many cold and flu
• digoxin – used to treat heart problems
• anti-inflammatory medicines such as phenylbutazone or aspirin
• propanolol – used to treat high blood pressure and heart
• ketamine – used as an anaesthetic. If you need to have an
operation, please tell your doctor or anaesthetist that you are
Pregnancy and breast-feeding:
If you are pregnant or breast-feeding, think you may be pregnant or
are planning to have a baby, ask your doctor or pharmacist for
advice before taking this medicine. Your doctor will decide if you
should continue treatment with levothyroxine whilst you are
pregnant, particularly in the first three months of your pregnancy.
Driving and using machines
This medicine should not affect your ability to drive and use
Levothyroxine Tablets contain lactose:
This medicine also contains lactose, a sugar. If you have been told
by your doctor that you have an intolerance to some sugars, contact
your doctor before taking this medicine.
3. HOW TO TAKE LEVOTHYROXINE TABLETS
Always take this medicine exactly as your doctor or pharmacist has
told you. Check with your doctor or pharmacist if you are not sure.
You may be taking this medicine for the rest of your life.
Your dose will be decided by your doctor and will depend on the
results of your blood tests. The dose you should take will be on the
label attached by your pharmacist. Swallow the tablets with
plenty of water. You should usually take your tablets before breakfast
or your first meal of the day.
The recommended starting dose is 50 – 100 micrograms every day.
Your doctor may increase the dose you take every 3 – 4 weeks by 50
micrograms until your thyroxine levels are correct. Your final
daily dose may be up to 100 – 200 micrograms daily.
Patients over 50 years of age:
The recommended starting dose will be no more than 50
micrograms every day. The dose may then be increased by 50
micrograms every 3 – 4 weeks until your thyroxine levels are correct.
Your final daily dose will be between 50 – 200 micrograms daily.
Patients over 50 years of age with heart problems:
The starting dose will be 25 micrograms every day or 50 micrograms
every other day. The dose may be increased by 25 micrograms
every 4 weeks until your thyroxine levels are correct.
Your final daily dose will usually be between 50 – 200 micrograms
Use in children:
For young children, your doctor is likely to prescribe Levothyroxine
Oral Solution instead of tablets.
Congenital hypothyroidism in infants:
This is a condition where your baby has been born with a thyroid
gland that does not produce enough thyroxine. The starting dose is
10 -15 micrograms/kg bodyweight per day for the first three months.
The dose will then be adjusted depending on how your baby
responds to the treatment.
Acquired hypothyroidism in children:
This is a condition where your child’s thyroid gland stops working
properly because it has been attacked by their immune system, e.g.
in children with an autoimmune disease or following a viral
infection. The starting dose is 12.5 – 50 micrograms per day. The
dose will then be increased every 2 - 4 weeks depending on how
your child responds to the medicine.
This is a condition where children and adolescents develop severe
hypothyroidism (produce very low levels of thyroid hormones). The
starting dose is 25 micrograms every day. The dose will then be
increased by 25 micrograms every 2 – 4 weeks until your child
shows mild symptoms of hyperthyroidism (a condition where the
thyroid gland produces too much thyroxine). The dose will then be
If you take more Levothyroxine tablets than you should
If you (or someone else) swallow a lot of the tablets at the same time,
or you think a child may have swallowed some, contact your nearest
hospital casualty department or tell your doctor immediately. Signs
of an overdose may include: fever, chest pain (angina), racing or
irregular heartbeat, muscle cramps, headache, restlessness,
flushing, sweating and diarrhoea. These signs can take up to 5 days
to appear. Take any remaining tablets and this leaflet with you so that
the medical staff knows exactly what you have taken.
If you forget to take Levothyroxine tablets:
If you forget to take a dose take it as soon as you remember unless it
is nearly time for your next dose. Do not take a double dose to make
up for a forgotten dose. If you forget to give your child their dose,
contact your doctor or pharmacist for further advice.
If you stop taking Levothyroxine tablets:
These tablets are for long term use. You may need to take them for
the rest of your life. Do not stop taking the tablets unless your doctor
has told you to do so.
If you have any further questions on the use of this medicine, ask
your doctor, pharmacist or nurse.
4. POSSIBLE SIDE EFFECTS
Like all medicines, this medicine can cause side effects, although not
everybody gets them.
Stop taking the tablets and go to hospital at once if you have:
• a rare allergic reaction such as swelling of the face, tongue, lips
and throat, difficulty breathing, severe itching of your skin with
raised lumps, joint pain, sensitivity to the sun, general feeling of
being unwell. You may need urgent medical attention.
Some patients may experience a severe reaction to high
levels of thyroid hormone. This is called a “thyroid crisis” and
you should contact your doctor immediately if you have any
of the following symptoms:
• very high temperature; fast heart rate; irregular heartbeat; low
blood pressure; heart failure; jaundice; confusion; fits and coma.
Tell your doctor or pharmacist if any of the following side
effects continue, get worse or if you notice any other side
effects not listed.
Most of the side effects are similar to the symptoms of
hyperthyroidism (where the thyroid gland makes too much thyroxine)
and are due to your dose of the medicine being too high. They will
usually disappear after reducing the dose or stopping the tablets.
However, you must not change the dose or stop the tablets
without talking to your doctor first.
Not known (frequency cannot be estimated from the available
• high temperature, sweating
• weight loss
• tremor, restlessness, excitability, difficulty sleeping (insomnia)
• increased pressure around the brain in children that is not caused
by a tumour or other diseases (benign intracranial hypertension)
• chest pain (angina), pounding, irregular or fast heartbeat
• diarrhoea, vomiting
• muscle cramps, muscle weakness
• deformity of the skull in infants caused by the early closure of
joints in the skull bone (craniostenosis)
• growth in children may slow or stop due to changes in bone
• irregular periods
• intolerance to heat
• temporary hair loss in children.
Reporting of side effects:
If you get any side effects, talk to your doctor, pharmacist or nurse.
This includes any possible side effects not listed in this leaflet. You
can also report side effects directly via the Yellow Card Scheme at:
By reporting side effects you can help provide more information on
the safety of this medicine.
5. HOW TO STORE LEVOTHYROXINE TABLETS
Keep this medicine out of the sight and reach of children.
Do not use this medicine after the expiry date which is stated on the
carton after EXP. The expiry date refers to the last day of that month.
Do not store above 25°C. Store in the original package in order to
protect from light and moisture.
Do not throw away any medicine via wastewater or household waste.
Ask your pharmacist how to throw away medicines you no longer
use. These measures will help protect the environment.
6. Contents of the pack and other information
What Levothyroxine Tablets contain:
- The active substance is anhydrous levothyroxine sodium. This
leaflet concerns two strengths of Levothyroxine tablets. Each
strength contains respectively 50 and 100 micrograms of
anhydrous levothyroxine sodium.
- The other ingredients are sodium citrate, lactose, maize starch,
acacia powder and magnesium stearate.
What Levothyroxine Tablets look like and contents of the
Each tablet is scored on one side and engraved on the other with
50mcg – FW21
100mcg – FW31.
They are packed in a blister pack of 28, 56 or 112 tablets and
polypropylene containers of 28, 56, 100, 112 or 1000 tablets. Not all
pack sizes may be marketed.
Marketing Authorisation Holder:
Mercury Pharma (Generics) Ltd., Capital House, 85 King William
Street, London, EC4N 7BL, UK
Custom Pharmaceuticals Ltd., Tecore House, Conway Street,
Hove, East Sussex, BN3 3LW, UK
This leaflet was last revised in September 2016.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.