Key takeaways:
Thyroid hormone replacement medications include levothyroxine (Synthroid and others), liothyronine (Cytomel), and desiccated thyroid (Armour Thyroid, NP Thyroid, and others). Levothyroxine is often considered the first-choice option.
You should take levothyroxine and other thyroid hormone medications on an empty stomach, at least 4 hours before or after other medications and dietary supplements.
Typically, you’ll need to take thyroid hormone medications for life. Stopping your medication can cause hypothyroidism symptoms to come back. Let your prescriber know about any side effects that occur during treatment.
GoodRx can help you save over 80% off the cost of generic levothyroxine. You can also access brand-name Levoxyl, Cytomel, Armour Thyroid, and NP Thyroid at exclusive cash prices with a free GoodRx discount. Manufacturer savings cards and patient assistance programs are also available.
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Levothyroxine and other thyroid hormone replacement medications help reverse the signs and symptoms of hypothyroidism. You take them by mouth to restore your body’s thyroid hormones to an adequate level.
Knowing how to take levothyroxine is key to getting the most from your treatment. Here are seven pharmacist-backed tips for taking thyroid hormone medications the right way.
1. Get the same type of thyroid medication from your pharmacy every time
Thyroid replacement medications restore your body’s thyroid hormones to an adequate level. They each contain a version of the thyroid hormones found in the body: thyroxine (T4), triiodothyronine (T3), or both.
The three types of medication prescribed to treat hypothyroidism are:
Levothyroxine (Synthroid, Levoxyl, Tirosint, Unithroid), which contains lab-made T4
Liothyronine (Cytomel), which contains lab-made T3
Desiccated thyroid (Armour Thyroid, NP Thyroid), which contains T3 and T4 from animal sources (usually a pig)
Levothyroxine and its brand-name counterparts are considered first-choice medications for hypothyroidism. Liothyronine is typically considered if levothyroxine isn’t effective on its own. But desiccated thyroid medications aren’t recommended by the FDA or the American Thyroid Association.
Since each type of thyroid hormone medication contains different amounts of T3 and/or T4, you shouldn’t switch from one type of thyroid hormone to another without your healthcare team's approval.
The hormone levels in most thyroid replacement medications can also differ slightly from one manufacturer to the next — even if the medication name is the same. For this reason, it’s best to stick to the same manufacturer of your medication as well whenever possible.
Sometimes, your pharmacy may change manufacturers based on what’s currently available. You’ll know when this happens because your medication will look slightly different. Each manufacturer has a unique color and/or marking for their version. So if your medication looks different than usual, it’s likely the manufacturer was changed. Check with your pharmacy to make sure, and ask if your preferred brand or manufacturer is available.
If you do change manufacturers, let your healthcare team know. They may want to do blood work to see if you need a dose adjustment.
2. Take your hypothyroidism medication on an empty stomach
Certain foods, such as whole wheat bread, papaya fruit, and soy-containing products, can prevent your body from absorbing your full dose of thyroid hormone. The same goes for coffee, fruit juices, and milk-based products. That’s why taking thyroid hormone medications on an empty stomach is so important.
When is the best time to take levothyroxine
It’s typically recommended to take most thyroid medications in the morning — ideally 30 minutes to 1 hour before your first meal of the day. But if the first thing in the morning isn’t best for you, try taking it before bedtime instead. Your body absorbs thyroid medications just as well when taken on an empty stomach at the end of the day (at least 4 hours after your last meal).
The key with all hypothyroidism medications is to remain consistent with when and how you take them. This helps keep your thyroid hormone levels stable.
When determining the best time to take your thyroid medication, consider these questions:
Do you take any supplements or medications that can affect your thyroid medication? If so, what time of day do you take those?
When do you normally eat your meals?
What time of day is easiest for you to remember to take your thyroid medication?
You’ll want to choose a time that’s 4 hours apart from other medications and 1 hour before or 2 hours after a meal. If you’re having trouble remembering to take your medication, consider using a daily pill organizer or medication reminder app to help you.
3. Separate thyroid medications from other medications and supplements
Minerals like iron, aluminum, and calcium can bind to levothyroxine and keep your body from absorbing the medication properly. This means you won’t get the full dosage and your thyroid hormone levels will likely be lower than they should be.
You can still take supplements or antacids that contain these minerals. You just need to separate them from levothyroxine by at least 4 hours. It’s also best to separate your thyroid hormone medication from other medications and supplements you take.
Other medications can also interact with thyroid replacement medications. Many can decrease how much thyroid hormone your body absorbs. We’ve already discussed antacids and supplements with iron, calcium, or aluminum. Here are some other examples:
Proton pump inhibitors such as pantoprazole (Protonix)
Bile acid sequestrants such as cholestyramine (Prevalite)
Sevelamer (Renagel, Renvela)
Phenobarbital
Other medications, such as amiodarone (Pacerone), may increase thyroid hormone levels.
It's best to separate all other medications from your hypothyroidism medication. Aim to take your thyroid medication at least 4 hours before or after your other medications. If you start a new medication and notice signs of low or high thyroid hormone levels, let your healthcare team know.
4. Avoid ‘thyroid support’ or other herbal supplements without your healthcare team's approval
Your thyroid needs certain vitamins and minerals to make thyroid hormones. You may have heard that taking them can help treat hypothyroidism. Often, they’re even marketed as “thyroid support” supplements. Some examples include:
Iodine
Ashwagandha
Coleus forskohlii
Gum guggul
L-tyrosine
These supplements aren’t a replacement for prescription medications. While some may have early evidence they can help support thyroid function, there’s not enough safety data available to recommend them. And they can also have side effects and drug interactions of their own. Be sure to talk with your healthcare team before taking any supplements for your thyroid. They can help determine if a particular supplement is safe for you.
Some thyroid supplements may even contain actual thyroid hormone. If you take these along with your thyroid replacement therapy, you could end up with too much thyroid hormone — more on that later.
5. Give the medication several weeks to have its full effect
Hypothyroidism symptoms can be frustrating, and you might be anxious for some relief. You may notice a difference right away. But often, it can take time for thyroid hormone medications to work. It may take 1 to 2 weeks for liothyronine to reach optimal levels. Desiccated thyroid takes a little longer — about 2 to 3 weeks. And levothyroxine may take 4 to 6 weeks for full symptom relief.
Your healthcare team will likely bring you in for regular blood tests, especially when you’re first starting the medication. This helps them keep an eye on your dose and make sure it’s working the way it should. Let them know if your symptoms aren’t improving as expected.
6. Look out for side effects
Most of the side effects from thyroid hormone medications happen when your dose is too high, mimicking signs of hyperthyroidism. This can cause the following:
Anxiety
Weight loss
Sweating
Tremor
If you experience any of these symptoms, let your healthcare team know. They’ll likely check your blood levels to see if they need to lower your thyroid hormone dose. You should also let them know if your hypothyroidism symptoms return. This may include fatigue, weight gain, or dry skin, and can be a sign your dose is too low.
More serious side effects can also happen when you’re taking thyroid hormones. Some examples include:
Trouble breathing
Fast or irregular heartbeat
Seizures
While rare, these side effects may happen if your thyroid hormone levels are too high or too low. And heart-related side effects are more likely if you have a history of heart disease. If these side effects occur, seek immediate medical attention.
7. Don’t stop taking your thyroid medication on your own
Thyroid replacement therapy is a lifelong treatment for most people who take it. If you stop taking your medication, your hypothyroidism will return. This can lead to irritability, mood swings, and even reversible dementia. It also raises your risk of heart problems.
Over time, low thyroid hormone levels may result in a rare, life-threatening condition called myxedema coma. Symptoms can include:
Low body temperature
Slow heart rate
Low blood pressure
Severe fatigue
Coma
Dry, coarse skin
Sometimes, this condition is brought on when an infection or exposure to cold temperatures affects your thyroid hormone level. But it’s more likely if you stop taking your thyroid medication altogether. Keep in mind that missing a dose or two isn’t usually anything to worry about.
How to save on prescription thyroid medications
There are many ways to save on your prescription thyroid medication. GoodRx can help you navigate between GoodRx coupons, copay savings cards, and patient assistance programs to save money on your prescription.
Save on levothyroxine
Levothyroxine is available as a generic tablet and capsule. Levothyroxine tablets are also available as a number of brand-name products, including Synthroid, Levoxyl, and Unithroid. GoodRx can help you navigate ways to save on your levothyroxine prescription.
Save with GoodRx. Anyone with a valid prescription, regardless of insurance status, can use GoodRx to purchase a 30-day supply of brand-name Levoxyl at an exclusive cash price. You may pay as little as $4.00 for a 30-day supply of generic levothyroxine tablets with a free GoodRx coupon.
Save with a copay savings card: If you have commercial insurance, you could pay as little as $25 a month for Synthroid with a manufacturer savings card. Unithroid may cost as little as $3 a month with a manufacturer savings card.
Save with patient assistance programs: If you’re uninsured or underinsured, you may be eligible for Synthroid's patient assistance program, which offers the medication free of charge.
Save on liothyronine
There are ways to save on liothyronine, which is available as both a brand-name and generic medication.
Save with GoodRx: Anyone with a valid prescription, regardless of insurance status, can use GoodRx to purchase a 30-day supply of brand-name Cytomel at an exclusive cash price. Generic Cytomel’s price at certain pharmacies is as low as $13.27 per month with a GoodRx discount.
Save with patient assistance programs: If you’re uninsured or underinsured, you may be eligible for Cytomel's patient assistance program, which offers the medication at no charge.
Save on desiccated thyroid
There are ways to save on Armour Thyroid and NP Thyroid, which are available as brand-name medications.
Save with GoodRx: Anyone with a valid prescription, regardless of insurance status, can use GoodRx to purchase a 30-day supply of Armour Thyroid at an exclusive cash price. Exclusive savings are also available for NP Thyroid.
Save with a copay savings card: If you have commercial insurance, you may be eligible to pay as little as $35 for a 30- or 90-day prescription of Armour Thyroid using a savings card from the manufacturer.
Save with patient assistance programs: If you’re uninsured or underinsured, you may be eligible for Armour Thyroid’s patient assistance program, which offers the medication free of charge.
Frequently asked questions
Your prescriber will usually check your thyroid-stimulating hormone (TSH) levels to determine if you’re taking the right dose of thyroid medication. TSH is a hormone that tells your thyroid to make more thyroid hormones and release them into your blood.
If your TSH is high, your body doesn’t have enough thyroid hormone. So your prescriber may increase your dose. If your TSH is low, the opposite is true: your body might have too much thyroid hormone. So your prescriber may decrease your dose. It’s a good habit to keep track of your current dose, since it may change a few times until you find your sweet spot.
Constipation isn’t a common levothyroxine side effect. But it can be a symptom of hypothyroidism. So it may be a sign that your levothyroxine dose is too low. Let your prescriber know if you're experiencing constipation while taking levothyroxine. They can check your thyroid hormone levels to help determine the cause.
Yes, hypothyroidism can be fatal if left untreated for a long period of time. So you shouldn’t stop taking levothyroxine or other thyroid hormone medications unless your prescriber tells you to. If you’re experiencing side effects from your medication, they can usually be managed with dosage changes. So it’s better to discuss them with your prescriber than stop taking your medication altogether.
Your prescriber will usually check your thyroid-stimulating hormone (TSH) levels to determine if you’re taking the right dose of thyroid medication. TSH is a hormone that tells your thyroid to make more thyroid hormones and release them into your blood.
If your TSH is high, your body doesn’t have enough thyroid hormone. So your prescriber may increase your dose. If your TSH is low, the opposite is true: your body might have too much thyroid hormone. So your prescriber may decrease your dose. It’s a good habit to keep track of your current dose, since it may change a few times until you find your sweet spot.
Constipation isn’t a common levothyroxine side effect. But it can be a symptom of hypothyroidism. So it may be a sign that your levothyroxine dose is too low. Let your prescriber know if you're experiencing constipation while taking levothyroxine. They can check your thyroid hormone levels to help determine the cause.
Yes, hypothyroidism can be fatal if left untreated for a long period of time. So you shouldn’t stop taking levothyroxine or other thyroid hormone medications unless your prescriber tells you to. If you’re experiencing side effects from your medication, they can usually be managed with dosage changes. So it’s better to discuss them with your prescriber than stop taking your medication altogether.
The bottom line
Thyroid hormone replacement medications — levothyroxine (Synthroid and others), liothyronine (Cytomel), and desiccated thyroid (Armour Thyroid and others) — help restore low thyroid hormone levels. Levothyroxine is the preferred choice for most people.
It’s best to take thyroid hormone medications on an empty stomach, 4 hours apart from any other medications. Don’t switch between medications, and let your prescriber know about any side effects that occur during treatment. Being consistent with how and when you take your thyroid medication gives you the best results.
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References
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A-S Medication Solutions. (2025). ARMOUR THYROID-thyroid, porcine tablet [package insert].
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Mahajan, P. (2020). Switching levothyroxine brands frequently results in abnormal thyroid function tests. Clinical Thyroidology for the Public.
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Pawar, R. S., et al. (2022). Determination of thyroid hormones in dietary supplements using liquid chromatography-tandem mass spectrometry. Drug Testing and Analysis.
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