Key takeaways:

• Thyroid hormone medications include levothyroxine (Synthroid, Levoxyl, Tirosint, Unithroid), liothyronine (Cytomel), and desiccated thyroid (Armour Thyroid). They restore your body’s thyroid hormone levels when they’re lower than they should be. Levothyroxine is often considered the best medication for hypothyroidism.
• You should take all 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. Although rare, low thyroid hormone levels can lead to a life-threatening condition. 

Table of contents

Thyroid hormone meds

Tips for taking

Dose adjustments

Drug interactions

When to take

Bottom line

References

GoodRx Health

In the U.S., almost 1 in every 20 people older than 12 years old have hypothyroidism (low thyroid hormone levels). And most are taking medications to treat it. Thyroid hormone 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.

Even though these medications mimic a natural hormone in the body, they can still carry risks. Knowing how and when to take them can help ensure you’ll get the most out of your medication.

Common medications for hypothyroidism

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.

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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), 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. 

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How to take hypothyroidism medication the right way

You need a consistent amount of thyroid hormone to keep your body running properly. And taking your thyroid medication correctly is one important step in making this happen. Below, we discuss eight tips for taking thyroid medication. 

1. Get the same type of thyroid medication from your pharmacy every time

The hormone levels in most thyroid replacement medications can differ slightly from one manufacturer to the next. For this reason, it’s best to stick to one manufacturer for your thyroid medication. And you shouldn’t switch from one type of thyroid hormone to another without your healthcare provider’s approval.

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, 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 change manufacturers, let your healthcare provider know. They may want to do blood work to see if you need a change in your dose.

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.

It’s best to take most thyroid medications in the morning on an empty stomach — 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 at least 2 hours after your last meal of the day. 

3. Don’t take your medicine within 4 hours of taking iron-, aluminum-, or calcium-containing supplements or antacids

Minerals like iron, aluminum, and calcium can bind to levothyroxine. This can keep your body from absorbing levothyroxine properly. Which means you won’t get the full dosage, and your thyroid hormone levels will likely be lower than they should be. But you can still take supplements or antacids that contain these minerals. You just need to separate them from levothyroxine by at least 4 hours. This applies to other medications and supplements, as well.

4. Avoid ‘thyroid support’ or other herbal supplements without your healthcare provider’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
• Vitamin B-12
• Ashwagandha
• Coleus forskohlii
• Gum guggul
• L-tyrosine
• Selenium
• Zinc

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 provider before taking any supplements. 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 to get 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. Armour Thyroid takes a little longer — about 2 to 3 weeks. And levothyroxine may take 4 to 6 weeks for full symptom relief.

Your healthcare provider 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 common 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
• Insomnia
• Sweating
• Tremor

If you experience these symptoms, let your healthcare provider know. They’ll likely check your blood levels to see if they need to lower your 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. 

7. Let your healthcare provider know about serious side effects 

More serious side effects can happen when you’re taking thyroid hormones, though it’s rare. Some examples include:

• Chest pain
• 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.

8. 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 do you know you’re taking the right dose of thyroid hormone medication?

Your primary care provider may manage your hypothyroidism, or you may see an endocrinologist — a provider who specializes in the body’s hormones. 

During your office visits, you can expect to have your thyroid-stimulating hormone (TSH) levels checked. TSH is a hormone that tells your thyroid to make more thyroid hormones and release them into your blood. Your healthcare provider will likely want your TSH level between 0.4 and 4.5 mIU/mL.

If your TSH is high, your body doesn’t have enough thyroid hormone. So your provider may increase your dose of thyroid medication. If your TSH is low, the opposite is true — your body might have too much thyroid hormone. So your provider 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.

You can expect a TSH check once or twice yearly if your dose doesn’t change. If there are dose changes, you might have another TSH check 6 to 8 weeks after the change. 

Can I take other medications with my hypothyroidism medications?

There are several medications that 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 like 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 provider know.

What’s the best time to take levothyroxine and other hypothyroidism medications?

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.

The bottom line

Thyroid hormone medications — levothyroxine, liothyronine, and desiccated thyroid — help restore low thyroid hormone levels. Levothyroxine is the preferred choice for most people.

Thyroid hormone medications are best taken on an empty stomach, 4 hours apart from any other medications. Being consistent with how and when you take your thyroid medication gives you the best results.

Why trust our experts?

Written by:

Emilie White, PharmD

Emilie White is a clinical pharmacist with over a decade of hospital pharmacy experience. Her professional areas of interest include critical care as well as infectious and autoimmune diseases.

Edited by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

Reviewed by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 8 years and currently serves as a pharmacy editor for GoodRx.

References

AbbVie Inc. (2022). SYNTHROID® (levothyroxine sodium) tablets, for oral use [package insert]. 

American Thyroid Association. (n.d.). Q and A: Thyroxine preparations. 

View All References (8)

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