Proper Administration of Levothyroxine
Levothyroxine should be taken as a single daily dose on an empty stomach, one-half to one hour before breakfast with a full glass of water, and at least 4 hours before or after medications or supplements that can interfere with its absorption. 1
Correct Administration Technique
- Take levothyroxine once daily at the same time each day
- Take on an empty stomach, 30-60 minutes before breakfast
- Swallow with a full glass of water to avoid choking or gagging
- Wait at least 4 hours before taking:
- Iron supplements
- Calcium supplements
- Antacids
- Other medications that interfere with absorption
Common Administration Errors to Avoid
- Inconsistent timing: Taking levothyroxine at different times each day can affect absorption and efficacy
- Taking with food: Food can decrease absorption by up to 40%
- Concurrent medication use: Taking levothyroxine with other medications that interfere with absorption
- Inadequate water intake: Not taking with a full glass of water
- Improper storage: Not protecting from light and moisture
Special Populations
Children
- For pediatric patients who cannot swallow tablets:
- Crush the tablet and suspend in 5-10 mL of water
- Administer immediately by spoon or dropper
- Ensure the child ingests the full amount
- Do not store the suspension 1
Pregnant Women
- Pregnant women require careful monitoring and dose adjustments
- TSH should be checked every 4 weeks until stable 2
- Target trimester-specific TSH reference ranges
Monitoring Protocol
After starting or adjusting levothyroxine:
- Check thyroid function tests (free T4, TSH) after 4-6 weeks 2
- For primary hypothyroidism: Titrate until clinically euthyroid with normal TSH
- For secondary/tertiary hypothyroidism: Use free T4 levels (not TSH) to guide dosing, aiming for upper half of normal range 1
- Once stable, monitor every 6-12 months 2
Important Considerations
- The peak therapeutic effect may not be reached for 4-6 weeks after dose adjustment 1
- Levothyroxine absorption may be affected when taken within one hour of certain foods 1
- Do not administer with soybean-based infant formula 1
- Store at 20°C to 25°C (68°F to 77°F) and protect from light and moisture 1
By following these administration guidelines, patients can maximize the effectiveness of levothyroxine therapy and maintain optimal thyroid hormone levels.