Forgot Your Levothyroxine? What to Do After a Missed Dose

If you forgot your levothyroxine this morning, the short answer is: take it when you remember, unless your next dose is close, and don't panic. Levothyroxine stays in your body for days, so one late or missed tablet makes very little difference to your thyroid levels.

What should you do if you forget your levothyroxine?

MedlinePlus, the U.S. National Library of Medicine's drug guide, gives the standard rule: take the missed dose as soon as you remember, but if it is almost time for your next dose, skip the missed one and continue your usual schedule. It also says not to take a double dose to make up for a missed one [C1].

The American Thyroid Association (ATA) is more relaxed. Its patient page says it is fine to take the missed dose as soon as you remember, and that it is also safe to make up a missed dose by taking a double dose the next day. If you miss more than one or two doses, the ATA says to contact your doctor [C3].

These two sources don't fully agree on doubling, and only your prescriber knows your heart health, age and dose. The practical step is to ask your doctor or pharmacist once, while nothing is wrong, which rule they want you to follow.

Here is how the timing usually plays out:

When you remember	What usually makes sense	Note
Before breakfast, a little late	Take it now and delay breakfast 30-60 minutes	The label asks for an empty stomach, 30-60 minutes before breakfast [C2]
After coffee or breakfast	Take it later on an emptier stomach (or at bedtime), or take it now and accept a smaller dose absorbed today	Coffee and food reduce absorption [C6][C7]; a pharmacist can help you choose
After an iron or calcium supplement	Wait until at least 4 hours after the supplement	The label asks for a 4-hour gap from iron, calcium and antacids [C2]
In the evening	Taking it at bedtime is usually reasonable; go back to your usual time tomorrow	Bedtime dosing kept TSH stable in trials [C5][C8]
The next morning	Take today's dose; whether to add yesterday's is a question for your doctor	MedlinePlus says don't double [C1]; the ATA says doubling the next day is safe [C3]
After 2 or more missed days	Restart your normal dose and call your doctor	The ATA advises contacting your doctor after more than one or two missed doses [C3]

Why does one missed dose matter so little?

Levothyroxine is a long-acting hormone. According to the FDA prescribing information, its half-life is 6-7 days in people with normal thyroid function and 9-10 days in people with hypothyroidism [C2]. Half-life is the time it takes for the amount in your blood to fall by half.

So weeks of daily tablets build a large reserve, and skipping one day trims it only slightly. This is also why a dose change takes a while to show in your blood work: the label recommends checking TSH 6-8 weeks after any dose change [C2].

So a single forgotten pill is not an emergency, and it is not a reason to change your dose. A pattern of forgotten pills is different, because those small dips add up.

I remembered after breakfast or coffee: take it now or wait?

Levothyroxine absorbs best on an empty stomach, which is why the label says to take it 30-60 minutes before breakfast [C2]. Food and coffee get in the way.

In a crossover trial of 65 patients, taking levothyroxine with breakfast every day for 8 weeks raised the average TSH to 2.93 mIU/L, compared with 1.06 mIU/L when it was taken fasting [C6]. A higher TSH means less hormone was getting through. In a small study, swallowing levothyroxine with coffee cut the amount absorbed by about 27-36%, while water followed by coffee 60 minutes later did not [C7]. More on that in our guide to coffee and levothyroxine timing.

That gives you two reasonable options for a one-off:

• Take it now, with food in your stomach. You absorb somewhat less today, but given the long half-life, one partly absorbed dose matters little.
• Take it later on an emptier stomach, for example a few hours after your meal or at bedtime. Check first that you have not just had iron, calcium or an antacid, which need a 4-hour gap [C2].

If you are unsure which suits your routine, ask a pharmacist. Our article on why levothyroxine needs an empty stomach explains the absorption side in more detail.

Can you take a missed levothyroxine dose in the evening?

Usually, yes. In a randomized double-blind crossover trial of 90 patients, taking levothyroxine at bedtime instead of in the morning lowered TSH by 1.25 mIU/L, with no change in quality of life [C5]. A 2025 meta-analysis of eight trials found no significant difference in TSH between evening and morning dosing [C8].

The evidence is not perfectly uniform. In the breakfast trial above, bedtime dosing produced a higher average TSH (2.19 mIU/L) than fasting morning dosing (1.06 mIU/L) [C6]. So keep your usual routine most days; an occasional evening catch-up is still reasonable.

If you take it in the evening, a later spot, well after dinner, keeps your stomach emptier. Then return to your normal time the next morning. If you keep forgetting mornings, ask your doctor whether a permanent switch makes sense; bedtime levothyroxine dosing covers who it tends to suit.

What if you missed several days, and is weekly dosing an option?

If you missed two or more days, restart your normal daily dose and contact your doctor, as the ATA recommends [C3]. Don't try to catch up by taking several tablets at once unless your doctor tells you to. Also mention the missed days before any blood test; the ATA asks patients to be honest about them [C4]. Otherwise a high TSH could be read as a dose that is too low.

You may read that levothyroxine can be taken once a week. This has been studied in specific settings, mainly people who struggle to take a daily tablet. A 2021 meta-analysis of four trials (294 patients) found that once-weekly dosing gave a TSH about 1.85 mU/L higher at 6 weeks than daily dosing, and some people showed short-lived heart-function changes 2-4 hours after the large weekly dose [C9]. A 2025 meta-analysis of three weekly trials also found higher TSH, though still within the reference range [C8].

This is research, not a do-it-yourself plan: weekly or catch-up dosing is your doctor's decision to make and monitor, especially if you have heart disease or are older.

What about vomiting, illness, travel and time zones?

Vomiting. The label and MedlinePlus give no specific rule for vomiting soon after a dose [C1][C2]. Ask your pharmacist whether to take another tablet. If you cannot keep your tablets down for more than a day or two, call your doctor, since that counts as missed doses [C3].

Illness. Keep taking levothyroxine through a cold or a short stomach bug unless your doctor says otherwise. Absorption is lower in malabsorption conditions [C2], so ongoing diarrhea is worth mentioning at your next check.

Travel and time zones. With a 6-7 day half-life [C2], a dose that comes a few hours early or late on a travel day does not matter much. A simple approach is to take it on waking in the new time zone and keep the usual empty-stomach gap before breakfast. Pack your tablets in your carry-on; our travel guide for thyroid medication has a checklist.

How can you stop forgetting your levothyroxine?

A few habits make the tablet hard to miss:

• Anchor it to something you never skip, like turning off your alarm or using the bathroom, and keep the bottle there with a glass.
• Use a weekly pill organizer. One glance tells you whether today's tablet is gone.
• Set a phone alarm with a label, not just a sound.
• Plan the morning around it. If coffee is the moment you remember, put the tablet next to the coffee maker and take it before brewing.

Thyra's medication timing feature helps with that last step: it plans your coffee, breakfast and supplement windows around your levothyroxine time, so the 30-60 minute wait and the 4-hour gap from iron or calcium are already worked out. If your schedule makes mornings hard, taking levothyroxine correctly walks through the options.

When to talk to your doctor

Contact your doctor or pharmacist if:

• You missed more than one or two doses in a row [C3].
• You miss doses often, for example several times a month. Your TSH may drift, and a different routine could help.
• You have symptoms of low thyroid hormone after missed days, such as feeling cold, tired, constipated, low in mood or forgetful [C4].
• You are pregnant or trying to conceive. The ATA notes that you will likely need a higher dose in pregnancy, typically 20-30% more, so missed doses matter more; contact your doctor as soon as you know [C3]. See levothyroxine in pregnancy.
• You took extra by mistake and feel a racing heart, chest pain or shakiness. The label lists these among the signs of too much thyroid hormone [C2].

Frequently asked questions

Is it bad to miss one day of levothyroxine?

For most people, no. With a half-life of 6-7 days (9-10 days in hypothyroidism), one missed tablet changes your hormone levels very little [C2]. Take it when you remember, or skip it if your next dose is close [C1].

Should I take two levothyroxine tablets the next day?

Sources differ. MedlinePlus says not to double [C1], while the American Thyroid Association says making up a missed dose with a double dose the next day is safe [C3]. Ask your doctor which rule fits you, ideally before it happens.

Can I take levothyroxine with breakfast if I forgot?

As a one-off, yes, but you will absorb less that day. Taking it with breakfast every day raised average TSH from 1.06 to 2.93 mIU/L in one trial [C6]. Taking it later on an emptier stomach or at bedtime is the alternative.

Can I take my missed levothyroxine at night?

Usually yes. Bedtime dosing has been tested in randomized trials, and a 2025 meta-analysis found TSH similar to morning dosing [C5][C8]. Take it well after dinner and go back to your usual time the next day.

Do I need to tell my doctor about missed doses before a blood test?

Yes. The ATA lists missed doses among the things to tell your doctor honestly [C4]. Missed days can shift your result, and your doctor may otherwise read it as a dose that is too low.

Bottom line

One forgotten levothyroxine tablet rarely matters, because its half-life is 6-7 days or longer [C2]. Take it when you remember unless the next dose is close, and settle the "double or not" question with your doctor ahead of time [C1][C3]. If you have missed more than one or two doses, are pregnant, or keep forgetting, call your doctor and build a routine around a fixed daily cue.