Skip to Content

UK Edition. Click here for US version.



View full screen / Print PDF » Download PDF ⇩
Levothyroxine 50micrograms and 100micrograms tablets
Read all of this leaflet carefully before
you start taking this medicine.
Keep this leaflet. You may need to read
it again.
If you have any further questions, ask your
doctor or pharmacist.
This medicine has been prescribed for you.
Do not pass it on to others. It may harm
them, even if their symptoms are the same
as yours.
• Thyroxine is a hormone produced by
the thyroid gland. Levothyroxine is
used to replace thyroxine in people
whose thyroid gland does not work
properly. You will usually need to take
this medicine for the rest of your life and
must not stop taking it, or change the
dose, without speaking to your doctor
• This medicine can affect the way other
medicines work (See Section 2‘Taking
other medicines’). If you take medicines
to control diabetes or warfarin to
prevent blood clots, the dose may need
to be adjusted by your doctor when you
start taking levothyroxine tablets.
• You will start off taking a low dose of this
medicine (See Section 3 ’How to take’).
Your doctor will then increase the dose
gradually at 3-4 week intervals until
your thyroxine levels are corrected. This
will help to reduce the chance of side
• You will need regular blood tests whilst
you are taking this medicine.

• These tablets can be taken by both
adults and children. If you are giving
this medicine to your child make sure
you know how many and when to give
the tablets (See Section 3 ’How to take’)
and what side effects to look out for (See
Section 4 ’Possible side effects).

2 Before you take Levothyroxine

Do not take this medicine if you:
• are allergic to levothyroxine or to any of
the other ingredients (see section 6).
• suffer from an overactive thyroid
gland that produces too much thyroid
hormone (thyrotoxicosis)
• have any condition that affects your
In this leaflet
adrenal glands (your doctor will be able
1 What Levothyroxine is and what
to advise you if you are not sure)
it is used for
• If any of these apply to you, do not take
2 Before you take
this medicine and go back to your doctor
to discuss your treatment.
3 How to take
Check with your doctor or pharmacist
4 Possible side effects
before taking Levothyroxine tablets if you:
5 How to store
• have suffered with an under active
6 Further information
thyroid gland for a long time
• suffer from heart problems including
1 What Levothyroxine is and what it
angina, coronary artery disease or high
is used for
blood pressure.
Thyroxine is a hormone which is
• are being treated for diabetes. The dose
produced naturally in the body by the
of your anti-diabetic medicine may need
thyroid gland. Levothyroxine is a synthetic
to be changed as levothyroxine can raise
version of this hormone. Thyroxine
blood sugar levels.
controls how much energy your body
• are over 50 years of age.
uses. When the thyroid gland does not
produce enough thyroxine (a condition Blood tests
Before you start taking levothyroxine
known as hypothyroidism), many of
your doctor will do a blood test to see
the body’s functions slow down. Some
how much thyroxine your thyroid gland
of the most common symptoms of
is making and what dose of the medicine
hypothyroidism are:
you will need. Once you start taking the
• tiredness
medicine your doctor will want you to
• weight gain
have regular blood tests to see how well
• feeling depressed
the medicine is working.
Levothyroxine tablets are used to
Taking other medicines
replace the thyroxine that your thyroid
gland cannot produce and prevent the Many medicines affect the way
levothyroxine works. The effects of
symptoms of hypothyroidism. Before
other drugs may also be affected by
starting your treatment your doctor will
carry out a blood test to work out how
much levothyroxine you need.

You must tell your doctor if you
are taking or start taking any other
medicines, including over the counter
medicines, herbal remedies and vitamin
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 the
• sucralfate – used to treat and prevent
stomach and duodenal ulcers

colestyramine and colestipol – used to
treat high level of fat in the blood

polystyrene sulphone resin – used to
reduce high levels of potassium in the
• medicines containing iron that are taken
by mouth

rifampicin – used to treat infections
• imatinib – used to treat certain types of

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 therapy

corticosteroids such as hydrocortisone
and prednisolone – used to treat

amiodarone – used to treat an irregular
heart beat
The following may be affected by

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 (epinephrine - used
to treat severe allergic reactions) or
phenylephrine (a decongestant found
in many cold and flu treatments)

digoxin – used to treat heart problems
• anti-inflammatory medicines such as
phenylbutazone or aspirin

propranolol – used to treat high blood
pressure and heart problems

ketamine – used as an anaesthetic. If
you need to have an operation, please
tell your doctor or anaesthetist that you
are taking levothyroxine.
Pregnancy and breast-feeding
If you are pregnant particularly in the
first three months of your pregnancy,
planning to become pregnant or are
breast-feeding, tell your doctor or
pharmacist before taking this medicine.
Your doctor will decide if you should
continue treatment with levothyroxine
whilst you are pregnant.

Important information about some of Giving these tablets to children:
the ingredients
The dose for children depends on their
If you have been told by your doctor that
age, weight and the condition being
you have an intolerance to some sugars,
treated. Your child will be monitored to
contact your doctor before taking this
make sure he/she gets the right dose.
medicine, as it contains lactose.
You should give them their medicine at
least half an hour before breakfast or
3 How to take
their first meal of the day. If necessary, the
You may be taking this medicine for the
tablets can be dissolved in 10-15ml of
rest of your life. Always take Levothyroxine
water and given with some more liquid
tablets exactly as your doctor has told you.
(5-10ml). The dissolved tablets should
If you are not sure, check with your doctor
be taken straight away. Do not keep the
or pharmacist. Your dose will be decided
solution to give to your child later.
by your doctor and will depend on the
results of your blood tests. The dose you Congenital hypothyroidism in infants:
This is a condition where your baby has
should take will be on the label attached
been born with a thyroid gland that does
by your pharmacist. Swallow the tablets
not produce enough thyroxine. The starting
with plenty of water. You should usually
dose is 10 -15 micrograms/kg bodyweight
take your tablets before breakfast or your
per day for the first three months. The
first meal of the day.
dose will then be adjusted depending
on how your baby responds to the
The usual starting dose is 50-100
micrograms every day. Your doctor
Acquired hypothyroidism in children:
may increase the dose you take every
This is a condition where your child’s thyroid
3-4 weeks by 50 micrograms until your
thyroxine levels are correct. Your final daily gland stops working properly because it has
been attacked by their immune system, e.g.
dose may be up to 100-200 micrograms
in children with an autoimmune disease or
following a viral infection. The starting dose
Patients over 50 years of age:
is 12.5 to 50 micrograms a day. The dose
The usual starting dose will be no more
should be increased gradually every 2 to
than 50 micrograms every day. The dose
4 weeks depending on how your child
may then be increased by 50 micrograms
responds to the medicine.
every 3-4 weeks until your thyroxine levels
Juvenile myxoedema:
are correct. Your final daily dose will be
This is a condition where children and
between 50-200 micrograms daily.
adolescents develop severe hypothyroidism
Patients over 50 years with heart
(produce very low levels of thyroid
hormones). The starting dose is 25
The starting dose will be 25 micrograms
micrograms every day. The dose will
every day or 50 micrograms every other
then be increased by 25 micrograms
day. The dose may be increased by 25
every 2-4 weeks until your child shows
micrograms every 4 weeks until your
mild symptoms of hyperthyroidism
thyroxine levels are correct. Your final
(a condition where the thyroid gland
daily dose will usually be between 50-200
produces too much thyroxine). The dose
micrograms daily.
will then be reduced slightly.

In children over 1 year, initially 2.5-5
micrograms per kg of bodyweight a day
should be taken.
If you take more Levothyroxine 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 any, 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.
If you forget to take Levothyroxine
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. If you forget to give your child their
dose, contact your doctor or pharmacist
for further advice.
Stopping the 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.
4 Possible side effects

Some people may have side-effects when
taking this medicine.
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 throxine)
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.
• headache
• flushing
• 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
• 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 joins in the skull
bone (craniostenosis)
• growth in children may slow or stop due
to changes in bone growth
• 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

• Keep out of the reach and sight of
• Do not store above 25ºC. Store in the
original package. Keep container in the
outer carton.
• Do not use Levothyroxine tablets after
the expiry date stated on the label/
carton/bottle. The expiry date refers to
the last day of that month.
• Medicines should not be disposed of
via wastewater or household waste.
Ask your pharmacist how to dispose
of medicines no longer required. These
measures will help to protect the
6 Further information

What Levothyroxine tablets contain
• The active substance (the ingredient that
makes the tablets work) is anhydrous
levothyroxine sodium. Each tablet
contains either 50 micrograms or 100
micrograms of the active substance.
• The other ingredients are lactose,
magnesium stearate, maize starch,
stearic acid and pregelatinised maize
What Levothyroxine tablets look like
and contents of the pack
50 microgram tablets are white, circular,
biconvex, uncoated tablets.
100 microgram tablets are white, circular,
shallow convex, uncoated tablets.
Pack size is 28 and 1000 tablets.
Marketing Authorisation Holder and
Actavis, Barnstaple, EX32 8NS, UK.
This leaflet was last revised in June 2014

If you would like a leaflet with
larger text, please contact
01271 385257.

AAAF8528 50752083

Expand view ⇕

Source: Medicines and Healthcare Products Regulatory Agency

Disclaimer: Every effort has been made to ensure that the information provided here is accurate, up-to-date and complete, but no guarantee is made to that effect. Drug information contained herein may be time sensitive. This information has been compiled for use by healthcare practitioners and consumers in the United States. The absence of a warning for a given drug or combination thereof in no way should be construed to indicate that the drug or combination is safe, effective or appropriate for any given patient. If you have questions about the substances you are taking, check with your doctor, nurse or pharmacist.