What Happens If I Accidentally Took 2 Thyroid Pills?

Taking two thyroid pills by accident is one of the most common medication slip-ups, and for most people a single double dose is unlikely to cause serious harm.1Missouri Poison Center. What Happens If I Take Too Much Thyroid Medicine? Many people notice nothing at all, and those who do usually feel only mildly keyed up for a short time.2Pillo. Accidentally Took Double Dose of Levothyroxine (Synthroid): What to Do Thyroid hormone works slowly and lingers in the body for days, so one extra pill adds only a little to what is already there. People with heart disease are the main exception and should get advice promptly.3PubMed Central. Levothyroxine Treatment and the Risk of Cardiac Arrhythmias – Focus on the Patient Submitted to Thyroid Surgery

What You Might Feel After a Double Dose

If you feel anything, it will most likely be one of these mild effects:

If you do notice something, it may feel like having had too much coffee: a little jittery, a little warm, heart a bit quick. These feelings fade on their own as the extra hormone slowly clears.

Poison control advises watching for symptoms over the next few days, not just the first hours.10Missouri Poison Center. What Happens If I Take Too Much Thyroid Medicine? In children who swallowed large amounts, symptoms sometimes appeared as late as 6 to 11 days afterward.11Thyroid Research and Practice. Accidental levothyroxine ingestion in children: Review of four cases

Sleep and mood may also shift briefly. Too much thyroid hormone commonly brings anxiety, irritability and trouble sleeping.12Brazilian Journal of Implantology and Health Sciences. RELATIONSHIP BETWEEN MOOD DISORDERS AND THYROID CHANGES13PubMed Central. Thyroid Dysfunction and Sleep Disorders

It can be hard to tell hormone jitters from plain worry about the mistake, which can itself make your heart race. A brief sense of worry that settles may just be nerves, while steady shakiness, sweating and a fast pulse that last for hours may point more toward the hormone, though neither pattern is a sure test. Either way, mild feelings don’t call for emergency care.

Why One Extra Pill Usually Isn’t a Big Deal

Most thyroid pills contain levothyroxine, also called T4, a stored form of thyroid hormone your body converts as needed. Your body doesn’t take in all of it: only about 60 to 80% of each pill is absorbed.14European Endocrinology. A Review of the Pharmacokinetics of Levothyroxine for the Treatment of Hypothyroidism Food lowers it further, from about 79% to about 64% when you take the pill with a meal.15European Endocrinology. A Review of the Pharmacokinetics of Levothyroxine for the Treatment of Hypothyroidism If your second pill came with breakfast, even less of it reached your blood.

Levothyroxine also stays in the body a long time: half of it is still there after about 6 to 7.5 days.16European Endocrinology. A Review of the Pharmacokinetics of Levothyroxine for the Treatment of Hypothyroidism That means you carry roughly a week’s worth of hormone at any moment, so one extra pill raises the total by only a modest amount. And more than 99.8% of the hormone in the blood is bound to carrier proteins and not active.17European Endocrinology. A Review of the Pharmacokinetics of Levothyroxine for the Treatment of Hypothyroidism

The conversion step adds another cushion. Only about a third of T4 is converted into T3, the active hormone.18PubMed. The extrathyroidal conversion rate of thyroxine to triiodothyronine in normal man This slow conversion acts as a buffer, and in large overdoses the body can even make more of an inactive form to delay effects.19Journal of Endocrinology, Metabolism and Diabetes of South Africa. A rare case of levothyroxine overdose

Pills that contain T3 are different. T3 is the active hormone and clears in about a day instead of a week,20European Endocrinology. A Review of the Pharmacokinetics of Levothyroxine for the Treatment of Hypothyroidism Desiccated thyroid such as Armour contains both T4 and T3. If your pill contains T3, mention it when you call for advice.

Typical daily doses are usually 25 to 200 micrograms, while serious overactive-thyroid effects have been reported with doses above 5,000 micrograms.21Journal of Endocrinology, Metabolism and Diabetes of South Africa. A rare case of levothyroxine overdose Two pills is a tiny fraction of that.

What to Do Right Now

There’s no need to panic after doubling up once.22Missouri Poison Center. What Happens If I Take Too Much Thyroid Medicine? Don’t try to make yourself vomit, because it doesn’t help.23Missouri Poison Center. What Happens If I Take Too Much Thyroid Medicine? Contact your healthcare provider, pharmacist, or poison control for advice as soon as you can.24Pillo. Accidentally Took Double Dose of Levothyroxine (Synthroid): What to Do

In the US, Poison Help is 1-800-222-1222; in Canada, it’s 1-844-764-7669.25Pillo. Accidentally Took Double Dose of Levothyroxine (Synthroid): What to Do The webPOISONCONTROL online tool gives the same guidance without a phone call.26Poison Control. Synthroid (levothyroxine): Side effects, interactions, and overdose The help is free, confidential and available 24 hours a day.27Poison Control. Synthroid (levothyroxine): Side effects, interactions, and overdose

Before you call, read the label for the strength in micrograms and count how many pills you took in total today, because those details decide what advice fits. Note the time you took each pill too, since the person you speak with will want to know how far apart they were.

On the call, expect questions about the drug name, strength, how many pills and when. They’ll also ask your age, weight and any heart conditions. For most adults the answer is to stay home and watch for symptoms.

A pharmacist is often the fastest option, since pharmacies field questions about doubled doses all the time and can see your prescription. Poison control is the better choice if you took far more than two pills, if a child or pet got into the bottle, or if it’s after hours and no pharmacist is reachable. Your doctor’s office is the right call if you have heart disease or your dose was recently changed, since they know your history.

Should You Skip Your Next Dose

Don’t skip or change your next dose on your own.28Pillo. Accidentally Took Double Dose of Levothyroxine (Synthroid): What to Do Levoxyl’s patient information says not to change your dose unless your healthcare provider tells you to.29Pillo. Accidentally Took Double Dose of Levothyroxine (Synthroid): What to Do So ask about tomorrow’s dose during the same call you make today.

Skipping isn’t needed to even out the extra pill. Because levothyroxine lasts about a week, small day-to-day changes average out, and skipping can create a new uneven pattern. Your provider may still adjust things based on your heart health or symptoms.

Taking it as usual means your normal time, with water, on an empty stomach. Don’t take a half pill to compensate, because that changes the amount you’re prescribed rather than correcting anything. If you feel a bit jittery tomorrow morning, that alone isn’t a reason to skip, but mention it to the person you called.

To prevent a repeat, use a weekly pill organizer so you can see at a glance whether today’s dose is gone. Taking the pill at the same moment daily, such as on waking, builds a habit, and keeping your bottles apart from family members’ pills avoids mix-ups.

Who Should Be More Careful

Heart rhythm problems are among the most common side effects of thyroid medicine.30PubMed Central. Levothyroxine Treatment and the Risk of Cardiac Arrhythmias – Focus on the Patient Submitted to Thyroid Surgery In people with existing heart disease, extra thyroid hormone makes rhythm problems easier to trigger or worsen.31PubMed Central. Levothyroxine Treatment and the Risk of Cardiac Arrhythmias – Focus on the Patient Submitted to Thyroid Surgery If you have heart disease, call your doctor that day rather than just waiting it out. Some other situations are worth mentioning on the phone: being older, being pregnant (your dose is closely managed), having recently started or changed doses, and taking pills with T3, which act faster.

Older hearts tend to be more sensitive to extra thyroid hormone, so a fast or irregular heartbeat is more likely to cause trouble. Symptoms like a racing pulse can be less obvious, so checking your pulse can be useful.

A heart-related warning looks like a heart that’s pounding, fluttering, skipping beats or racing while you sit still. Shortness of breath with light activity or chest tightness deserves prompt attention in anyone with heart disease. Feeling lightheaded or faint is another reason to call right away rather than wait to see if it passes.

Warning Signs That Need Urgent Care

When hormone levels climb too high, serious signs include chest pain, palpitations, a rapid pulse, heavy sweating and diarrhea.32Universal Drugstore. What are the side effects of too much Armour Thyroid? The most extreme form, thyroid storm, sends heart rate, temperature and blood pressure dangerously high and needs immediate treatment.33Universal Drugstore. What are the side effects of too much Armour Thyroid? This is linked to large overdoses or untreated overactive thyroid, not a single extra pill.34Journal of Endocrinology, Metabolism and Diabetes of South Africa. A rare case of levothyroxine overdose

Mild effects come on gently and fade, while emergency signs are intense, worsen over time, or interfere with breathing or thinking. A pounding heartbeat that doesn’t settle after resting for a while is more concerning than a brief flutter. Feeling very hot with a high fever, or becoming confused or unusually drowsy, should be treated as an emergency rather than something to wait out.

For chest pain, fainting or trouble breathing, call 911 or go to the emergency room. Don’t drive yourself if your heart is racing. Bring the pill bottle and tell staff how many pills you took and when. Chest pain after a double dose still deserves emergency care, even though two pills rarely cause serious toxicity, because it can come from a heart problem that the extra hormone merely uncovered.

If a Child Swallowed Your Pills

Young children usually do well. Among children aged 1 to 5 who swallowed levothyroxine, about 1 in 4 had symptoms, and all were minor and went away without treatment.35PubMed. Clinical effects of accidental levothyroxine ingestion in children Symptoms included a fast heartbeat, hyperactivity, fever, vomiting, diarrhea, sweating and flushing.36PubMed. Clinical effects of accidental levothyroxine ingestion in children Rarely, large amounts caused seizures or rhythm problems.37Thyroid Research and Practice. Accidental levothyroxine ingestion in children: Review of four cases How a child feels doesn’t track closely with how much they took,38PubMed. Clinical effects of accidental levothyroxine ingestion in children so call poison control even if the child seems fine.

In the first minutes, take any pills out of the child’s reach and gently remove any from their mouth. Don’t make the child vomit, and don’t give food or drink to dilute the medicine unless poison control tells you to.

Tell poison control how many pills may be missing and their strength, the child’s age and weight, and when it likely happened. They may advise watching for up to about 11 days because symptoms can be delayed.

If Your Dog or Cat Ate Your Thyroid Pills

If your pet swallows your thyroid medicine, veterinary care is needed.39Paloma Health. What To Do If Your Dog Swallows Your Thyroid Medication Signs include vomiting, diarrhea, a fast heart rate, panting, agitation or sluggishness, and tremors.40Pet Poison Helpline. Thyroid Medications Is Toxic To Dogs For large overdoses, vets may give activated charcoal and supportive care.41PubMed. Acute overdose of levothyroxine in a dog Call your vet or a pet poison helpline right away, with the bottle in hand. Human poison centers aren’t set up for animals, and you shouldn’t make a pet vomit without a vet’s instruction.

In the first few minutes, remove any remaining pills and secure the bottle, then check how many are missing and note the strength. Note your pet’s approximate weight and when it likely happened, since vets use these to judge how risky the amount is. Afterward, store pills where pets can’t chew through the bottle.

Getting Back on Track With Absorption

Calcium and iron supplements can make levothyroxine less effective by binding to it in the gut.42PubMed Central. Levothyroxine Interactions with Food and Dietary Supplements–A Systematic Review Taking calcium at the same time cut absorption by about 20 to 25%.43PubMed Central. Absorption of Levothyroxine When Coadministered with Various Calcium Formulations Many other medicines and drinks can interfere too.44PubMed Central. Medications and Food Interfering with the Bioavailability of Levothyroxine: A Systematic Review So take your pill on an empty stomach with water and keep supplements several hours apart.

Your pharmacist can confirm the right gap between levothyroxine and calcium or iron for your situation. If you take your thyroid pill at bedtime, the same principle applies to anything you take with dinner. Switching between with-food and empty-stomach days changes how much hormone you absorb, so keep your routine consistent and tell your doctor about any new supplements.