What to Do If You Miss a Dose of Levothyroxine
If you miss a dose of levothyroxine, take it as soon as you remember on the same day, even if it means taking two pills that day (one in the morning and the missed dose when remembered). 1, 2
Immediate Action Based on When You Remember
If You Remember the Same Day
- Take the missed dose as soon as you remember, regardless of the time 1
- You can safely take your regular morning dose and the missed dose on the same day without significant risk 2
- For levothyroxine specifically, the long half-life (approximately 7 days) means taking a double dose after a missed dose is actually the optimal strategy to maintain stable thyroid hormone levels 2
If You Remember the Next Day
- Do not take a double dose the next morning - simply resume your regular schedule 1
- Skip the missed dose entirely and continue with your normal daily dosing 1
- The long half-life of levothyroxine means missing a single dose will not cause immediate clinical problems 2
Why This Approach Works
The pharmacokinetic properties of levothyroxine make it uniquely forgiving of missed doses compared to other medications:
- Levothyroxine has a half-life of approximately 7 days, meaning drug levels decline slowly in your body 2
- Mathematical modeling demonstrates that taking a double dose after a missed dose for drugs with long half-lives (like levothyroxine) produces at most only slightly higher drug concentrations than perfect adherence 2
- This contradicts older recommendations that suggested avoiding double doses for long half-life medications 2
Monitoring and Follow-Up
- If you frequently miss doses, discuss adherence strategies with your physician, such as setting phone alarms or involving family members 3
- Continue your regular TSH monitoring schedule (every 6-8 weeks during dose adjustments, then every 6-12 months once stable) 1, 4
- A single missed dose will not significantly affect your TSH levels due to the medication's long half-life 2
Critical Considerations
Never adjust your regular daily dose on your own - only your physician should make dose changes based on TSH monitoring 1
- Missing multiple consecutive doses requires medical consultation, as this may necessitate dose re-evaluation 1
- If you miss doses frequently (suggesting adherence issues), your physician may need to reassess your treatment plan 3
- Pregnant women should be especially vigilant about adherence, as levothyroxine requirements increase 25-50% during pregnancy and missed doses could affect fetal development 1, 5
Alternative Dosing Strategy
Some patients may benefit from bedtime dosing instead of morning dosing, which has been shown to improve thyroid hormone levels and may improve adherence for those who frequently forget morning doses 6. Discuss this option with your physician if morning adherence is challenging.