What should a patient do if they miss a dose of levothyroxine (thyroid hormone replacement medication)?

What to Do If You Miss a Morning Dose of Levothyroxine

Take the missed levothyroxine dose as soon as you remember it, even if it's later in the day, unless it's close to your next scheduled dose.

Immediate Action for a Missed Dose

• Take the dose as soon as you remember, regardless of whether it's later in the morning, afternoon, or evening 1
• The general principle for missed medication doses is to take them when remembered rather than skip them entirely 1
• For levothyroxine specifically, taking a late dose is preferable to skipping it, as the drug has a long half-life (approximately 7 days) that minimizes the risk of significant fluctuations from timing variations 2, 3

When NOT to Take the Missed Dose

• Do not take the missed dose if you remember it very close to your next scheduled dose (within a few hours) 1
• Never double up doses by taking two tablets at once to "make up" for the missed dose 1
• If you realize you missed yesterday's dose when taking today's dose, just take today's dose normally and skip yesterday's entirely 1

Why This Approach Works for Levothyroxine

• Levothyroxine has an exceptionally long half-life, meaning drug levels change slowly in your body 2, 3
• Mathematical modeling demonstrates that taking a late dose of levothyroxine causes minimal deviation from optimal drug concentrations compared to skipping the dose entirely 2, 3
• A single missed dose will not cause immediate thyroid hormone deficiency due to the drug's pharmacokinetic properties 3
• Research shows that patients who take double doses after missed doses of long half-life medications like levothyroxine maintain more stable drug levels than those who skip doses, though doubling is generally not recommended for routine practice 3

Timing Considerations

• While levothyroxine is typically taken before breakfast on an empty stomach for optimal absorption, taking it later in the day (even before dinner) only minimally reduces therapeutic efficacy 4
• A study showed that changing administration from before breakfast to before dinner resulted in only a 1.47 µIU/mL increase in TSH and 0.35 µg/dL decrease in T4—clinically insignificant changes 4
• The most important factor is taking the dose, not the precise timing 4

Strategies to Prevent Future Missed Doses

• Set daily phone alarms or reminders to minimize the likelihood of forgetting doses 5
• Keep your medication in a visible location where you'll see it during your morning routine 5
• Consider using a pill organizer to track whether you've taken your daily dose 5
• Enlist support from a family member or partner to help remind you 5

Important Caveats

• If you frequently miss doses or have difficulty remembering to take levothyroxine in the morning, discuss alternative timing strategies with your physician 4
• Consistent daily adherence is crucial for maintaining stable thyroid hormone levels and achieving target TSH levels 5, 6
• Approximately 25% of patients on levothyroxine are unintentionally over- or under-treated due to inconsistent dosing patterns, emphasizing the importance of adherence 5
• If you miss multiple doses in a row, contact your healthcare provider rather than attempting to "catch up" on your own 1