Levothyroxine Sodium, a thyroid hormone, replaces or adds on to the natural thyroid hormones normally produced by the thyroid gland. Thyroid hormones help in many body functions related to growth and energy.
Levothyroxine Sodium is used to treat thyroid deficiency due to an underactive thyroid gland, inflammation of the thyroid gland and certain thyroid gland tumours.
Take Levothyroxine Sodium exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by your doctor.
Levothyroxine Sodium must be taken regularly for it to work well. Do not skip any doses. You may need to take Levothyroxine Sodium for some time before the full benefits can be felt. Continue to take it even when you feel better. Do not stop taking Levothyroxine Sodium unless instructed by your doctor.
Take Levothyroxine Sodium on an empty stomach half an hour before breakfast. Take with a full glass of water.
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and return to your normal dosing schedule.
DO NOT double a dose under any circumstances.
If you often forget to take your medicine, let your doctor and pharmacist know.
Alert your doctor if you have an overactive thyroid gland as this medicine may not be suitable for you.
Inform your doctor if you have any of the following conditions:
- heart disease such as heart attack, angina (chest pains)
- high blood pressure
- adrenal gland disease
Let your doctor know if you are pregnant or breastfeeding.
Do not switch brands unless instructed by your doctor. This is because different brands of Levothyroxine Sodium may have slightly different ways of working in your body.
Levothyroxine Sodium may cause any of the following side effects: diarrhoea, vomiting, increased appetite, weight loss, headache, fever, anxiety, tremors, restlessness, problems falling asleep and some temporary loss of hair.
Other side effects are less common but may be more serious. Alert your doctor if you develop chest pain, fast or irregular heartbeat, increased blood pressure, breathlessness, excessive sweating, inability to tolerate heat, agitation or muscle weakness and cramps. Women who experience menstrual irregularities should also notify their doctor.
Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Inform your doctor and pharmacist if you are taking any of these medicines:
- blood-thinning medicines e.g. warfarin
- medicines to treat depression e.g. lithium, imipramine, sertraline
- birth control pills and hormone replacement therapy e.g. oestrogens
- asthma medicine e.g. theophylline
- medicine to treat TB (lung infection known as tuberculosis) e.g. rifampicin
- heart medicines e.g. digoxin, amiodarone, propranolol
- medicines for pain and inflammatory conditions e.g. mefenamic acid, ibuprofen
- medicines for lowering cholesterol e.g. cholestyramine, simvastatin
- medicines for epilepsy e.g. phenytoin, carbamazepine
- other medicines such as lanthanum, orlistat, androgens
Do not take Levothyroxine Sodium together with antacids or supplements containing aluminium, calcium, iron, magnesium or zinc. These may affect the absorption of Levothyroxine Sodium. If you must take these medicines, take between meals or at least 4 hours after you have taken Levothyroxine Sodium.
This list does not include all medicines that may interact with Levothyroxine Sodium.
Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicine, supplements and medicines that you buy without a prescription.
Inform your doctor and pharmacist if you are taking soy-containing products.
Store in a cool, dry place away from the reach of children.
Medicines must not be used past the expiry date.