Levothyroxine

Please note: these are basic guidelines, refer to your doctor for a professional medical opinion.

Popular brand names:

Euthyrox

Drug group:

Thyroid hormone

Prescription needed?

Yes

What does it do?

• Levothyroxine is mainly used to treat hypothyroidism (underactive thyroid gland)
• It is also sometimes given in combination with carbimazole/propylthiouracil in the treatment of hyperthyroidism (overactive thyroid gland)
• Higher doses are used in the treatment of thyroid cancer

How does it work?

• The thyroid gland secretes two hormones (T3 and T4) which are responsible for optimal growth, development, function and maintenance of body tissues
• Levothyroxine is a synthetic form of T4, and is given when the natural hormone is deficient
• Hypothyroidism causes symptoms such as fatigue, weight gain and slowing of body functions

How should it be used?

• Levothyroxine should be taken in the morning, about an hour before breakfast
• Do not take levothyroxine tablets with coffee

What is the typical dosage?

Your doctor will recommend a dosage tailored to your need, but typically:

• Starting dose is 25–100mcg daily
• The dose can be increased at 3–4-week intervals as required, maximum dose 200mcg daily

How quickly will it start to work?

Within 48 hours, full beneficial effects may take several weeks  

How long will the effects last?

1–3 weeks                               
  

When should I stop using it?

Do not stop the drug without consulting your doctor     
          

Is it safe for prolonged use?

No special problems, regular tests of thyroid function are required

What are the possible side effects?

The following have been reported:

• More common: Side effects are rare and are usually due to over-dosage
• Less common: anxiety, agitation, diarrhoea, weight loss, sweating, flushing, muscle cramps, insomnia, tremors
• Report to your doctor before taking your next dose if you experience: palpitations, chest pain

What other considerations are important?

Dosage may be adjusted by your doctor under certain conditions.

• Certain health problems: high blood pressure, heart problems, diabetes
• Other medicines: oral anticoagulants, colestyramine, amiodarone, antiepileptic drugs, antidiabetic agents, sucralfate, antidepressants (esp tricyclic antidepressants), oral contraceptives
• Pregnancy and breast-feeding: No evidence of risk
• Children: Dosage depends on age and weight
• Over 60: Reduced dose usually necessary
• Driving and hazardous work: No known problems
• Alcohol: No known problems