top of page
horizontal logo.gif

Part 1:




What is Levothyroxine?

Levothyroxine is a synthetic version of thyroxine, the hormone – abbreviated as T4 – made and released by your thyroid gland. Levothyroxine is the active ingredient in many thyroid hormone replacement drugs that treat hypothyroidism. In hypothyroidism, your thyroid is underactive – or has been surgically removed – and can’t produce enough of the thyroid hormone your body needs to function.

What Are the Three Forms of Levothyroxine?

  1. Tablets -- There are three brand name levothyroxine tablets – Levoxyl®, Synthroid®, and Unithroid® – in the United States. There are also many companies making generic levothyroxine tablets.

  2. Capsules -- There is one brand name of levothyroxine capsules – Tirosint® – and no generic capsules.

  3. Oral solution – There is one brand name of levothyroxine oral solution -- Tirosint®-SOL – and no generic version.


Which Pharmaceutical Companies Manufacture Levothyroxine for the U.S. Market?


Levoxyl® Tablets


Synthroid® Tablets


Tirosint® Capsules / Tirosint®-SOL Oral Solution


Unithroid® Tablets


Generic Levothyroxine Tablets

Generic levothyroxine manufacturers include AHP, Alvogen, Amneal, API, A-S, Bryant Ranch, Denton, Direct Rx, HJ Harkins, Humco, Lannett, Lupin, Major, Medisca, Mylan, Neolpharma, Par, PD-Rx, Proficient, Provell, Quality Care, Sandoz, and others


How Should You Take Levothyroxine?


You should take levothyroxine in the morning, ideally on an empty stomach, at least 30 to 60 minutes before eating breakfast.


Experts also recommend you wait at least an hour after taking your levothyroxine before drinking coffee or milk, because both beverages can negatively affect absorption.


Levothyroxine absorption can also be affected by antacids that include calcium, aluminum hydroxide, and magnesium, iron and calcium supplements, multivitamins that contain iron or calcium, and beverages like calcium-fortified juices. You should take levothyroxine four hours before or after these medications, supplements, or drinks.


Note that other dietary factors can impair levothyroxine absorption, including:

  • Foods containing soy products

  • Foods containing cottonseed meal

  • Walnuts

  • Grapefruit juice

  • High-fiber foods and fiber supplements


For levothyroxine tablets and capsules, it’s recommended that you take them with a glass of water.


Tablets can be safely split. You can’t split levothyroxine capsules.


Tirosint-SOL oral solution is packaged in individual dosage ampules. You can take the liquid levothyroxine directly in your mouth, or dilute it in water.




What's in Your Levothyroxine?

The active ingredient in all levothyroxine drugs is the levothyroxine – the synthetic thyroid hormone -- itself. Like all medications, levothyroxine also includes excipients—the inactive and inert ingredients that serve as fillers and binders. 


The following is a list of excipients you’ll find in brand name and generic levothyroxine tablets. The darker orange color signifies the excipients most associated with sensitivity.


What’s in Tirosint® and Tirosint®-SOL?

Tirosint® capsules have three excipients: gelatin, glycerin, and water. Sensitivity or allergies to gelatin and glycerin are extremely rare.

Tirosint®-SOL oral solution has two excipients: glycerol and water. Sensitivity or allergies to glycerol are also extremely rare.

How Can Excipients Affect You?

Excipients can affect how well you absorb your levothyroxine. Switching from one brand name or generic levothyroxine tablet to another changes the excipients, and can affect how well you absorb your levothyroxine.

Keep in mind that excipients in your levothyroxine can change without advance notice. Changes to excipients are known to cause significant changes for patients, and in some cases, have even generated mass complaints to the Food and Drug Administration.

It’s estimated that at least 15% of the population is allergic or sensitive to various excipients in medications. Some signs and symptoms of allergy/insensitivity to excipients include:

  • Skin Rash

  • Hives

  • Itching

  • Swelling

  • Stomach Pain

  • Diarrhea

  • Bloating and Gas

  • Migraine

  • Severe Reaction/Anaphylaxis

Four excipients commonly found in many levothyroxine tablets are especially problematic for some patients:

  • Acacia: This pollen-producing tree/shrub can trigger sensitivities in the 30% of the public that has seasonal pollen allergies and hay fever

  • Lactose: This common ingredient in milk can trigger sensitivities in people who are lactose-intolerant, which is estimated by the National Institutes of Health at 65% of the population.

  • Crospovidone/Povidone/Iodine: Iodine can trigger symptoms in the estimated 3% of people who have an intolerance to this common excipient.

  • Glycolate/Starch Glycolate: This common excipient can include wheat starch and gluten, a problem for the estimated 1% of the population with celiac disease, and up to 6% who have gluten sensitivity.


Which Dyes Are Used in Levothyroxine?

Every dosage of levothyroxine in tablet form comes in a different color due to the addition of dyes. The only exception is the 50 mcg dosage tablets, which are white, and free of dyes.

The FDA has approved various dyes for use in the manufacture of levothyroxine tablets and considers them all safe for use in medications.  But are they truly safe? The British government and the European Union have already taken action to end the use of most dyes in medicines. And here in the U.S., the International Journal of Occupational and Environmental Health has said that testing on dyes is inadequate, and that because dyes are not essential ingredients, they should be removed. The Center for Science in the Public Interest, a consumer watchdog group, has petitioned the FDA to ban the use of dyes.  


Some people have known sensitivity to the dyes found in levothyroxine tablets. Here are some details on the dyes included in levothyroxine tablets.

  • FD&C Blue No. 1 Aluminum Lake: Can cause hypersensitivity reactions. In 2003, the FDA issued a Public Health Advisory to alert healthcare providers of toxicity associated with some uses.

  • FD&C Blue No. 2 Aluminum Lake: The Center for Science in the Public Interest says that it is not safe for human consumption. The Environmental Working Group cites numerous studies looking at the potential toxicity.

  • FD&C Red No. 27 Aluminum Lake: Classified as expected to be toxic or harmful in Canada.

  • FD&C Red No. 30 Aluminum Lake: Classified as expected to be toxic or harmful in Canada.

  • FD&C Red No. 40 Aluminum Lake: Can cause hypersensitivity reactions in some people.

  • FD&C Yellow No. 10 Aluminum Lake: Limited evidence of any toxicity.

  • FD&C Yellow No. 6 Aluminum Lake: Can cause hypersensitivity reactions in some people.


Note: Tirosint® capsules and Tirosint®-SOL oral solution contain no dyes.


How Do Levothyroxine Potency Differences Affect Your Treatment?


Levothyroxine has what the FDA refers to as a "narrow therapeutic index.” That means that even small variations in the amount of active levothyroxine can significantly affect whether it's effective for you.  The FDA, therefore, requires all levothyroxine drugs to fall within 95% to 105% of its stated potency.


Each manufacturer -- whether brand name or generic -- tends to have the same potency rate for all the different dosages of its levothyroxine. So, for example, Company A's levothyroxine may run at 95% potency, Company B's at 100% potency, and Company C's at 105%. This information is not, however, publicly available.

These potency differences can create a challenge for your treatment. How? Let’s look at an example.


Companies A and C each make a brand name or generic levothyroxine. Company A’s levothyroxine is 95% potency, and Company C is 105% -- both within the FDA guidelines.


Let’s say you are stable and feeling well on Company A’s levothyroxine, but you must switch to Company C -- a different brand or generic. This switch may occur due to product availability, cost issues, or insurance company mandates.

When you switch from Company A to Company C’s product, you get more medication – almost ¾ of a pill more medication, in fact, during a week of treatment. If you switch from Company C to Company A’s product, you get almost ¾ of a pill less medication in a week. Even that difference is enough to affect your response to treatment and change your thyroid test levels.


There’s another critical issue with potency: All levothyroxine drugs lose potency over time. That’s why they have an expiration date. The potency of levothyroxine tablets can degrade when exposed to light, heat, and moisture. (That’s a good reason NOT to store your levothyroxine tablets in the kitchen or bathroom, and instead, choose a cool, dark, dry spot!)  Levothyroxine capsules – individually packaged in blister-packs -- and levothyroxine oral solution – with doses individually packaged in ampules -- are more resistant to light, heat, and moisture compared to tablets.

The American Association of Endocrinologists (AACE), recognizing the issue of potency variations, has said: “Thyroid disease is best managed with consistent and precise treatment with the same brand of thyroid hormone."


The best way, then, to minimize any problems from potency issues is to take the same brand of levothyroxine.


What Are the Challenges of Taking Generic Levothyroxine?


Generic levothyroxine poses an additional challenge. Every time you get a refill of levothyroxine, it can come from a different generic manufacturer.


That means that with every refill, you can get levothyroxine with potency ranging from 95% to 105% of the stated dosage. And don’t forget that every generic levothyroxine has different excipients, which may change that medication’s effectiveness for you.


If you can’t take a brand name, there are three ways to help minimize the impact of potency and excipient changes from refill to refill of generic levothyroxine.

  1. First, if you get stabilized and feel well on a particular manufacturer’s generic levothyroxine, have a discussion with your pharmacist to see if he or she can ensure that you get refills only from that one generic manufacturer. This can be difficult or impossible with larger pharmacy chains and mail-order pharmacies but may be possible if you have a relationship with a smaller, independently owned local pharmacy.

  2. Second, get the largest possible quantity refill. If you can get a three- or six-month supply – instead of monthly refills – you reduce your risk of potency variations.

  3. Third, you can order generic levothyroxine online from the “Mail My Prescriptions” website. Mail My Prescriptions is the only site I found that lets you specify that a prescription is filled by generic levothyroxine from a specific manufacturer, in this case, Alvogen or Amneal. Mail My Prescriptions is located online at


Do You Need a Brand Name Levothyroxine?


There are some situations where a brand name drug is particularly important, because for these patients, reliable, consistent treatment is crucial, and fluctuations in potency can have serious outcomes. These include:

  • Pregnant women, whose thyroid treatment helps protect the neurological health of the developing baby, and helps prevent miscarriage, stillbirth, and premature birth

  • Babies born with congenital hypothyroidism and children with hypothyroidism, who need thyroid hormone for their neurological, intellectual, and physical growth and development

  • Thyroid cancer survivors on “suppressive therapy,” who need consistent treatment to achieve the low or undetectable thyroid stimulating hormone (TSH) levels that help prevent thyroid cancer recurrence.


If you are on generic levothyroxine and fall into these categories, talk to your health care provider about whether a brand name levothyroxine would be a better choice.


You should also consider switching from generic to brand name levothyroxine if:

  • Your thyroid test levels are not stable on generic levothyroxine

  • Your thyroid test levels are optimal, but you don't feel well and continue to have symptoms on your current dosage of generic levothyroxine

  • You have signs or symptoms or an allergy or sensitivity to a particular excipient and need a consistent formulation


When Should You Consider Switching from One Brand of Levothyroxine to Another?


If you are already taking a brand name levothyroxine, remember that the form, excipients, and dyes in your brand can change its effectiveness for you. Consider switching from one brand to another brand of levothyroxine when:

  • Your thyroid test levels are not stable on your current brand of levothyroxine

  • Your thyroid test levels are optimal, but you don't feel well and continue to have symptoms on your current brand of levothyroxine

  • You have signs or symptoms or an allergy or sensitivity to excipients in your current brand of levothyroxine

  • You are lactose-intolerant, and taking a brand of levothyroxine that includes lactose

  • You have seasonal allergies and are taking a brand of levothyroxine that includes acacia

  • You are sensitive to iodine and are taking a brand of levothyroxine that includes povidone/crospovidone

  • You are sensitive to gluten and are taking a brand of levothyroxine that includes starch glycolate


When Should You Consider Switching from Levothyroxine Tablets to Tirosint® Capsules or Oral Solution?


Tirosint® capsules were approved by the FDA in 2006 and became available in early 2007. Even though the drug has been available in the US since early 2007, many thyroid patients and physicians are not familiar with this levothyroxine treatment option. Tirosint®-SOL oral solution was released in the U.S. in early 2019.


Tirosint® and Tirosint®-SOL feature a liquid form of levothyroxine and are made without the common excipients found in levothyroxine tablets that can trigger allergies or sensitivities.


Research shows that if you have a gastrointestinal or digestive condition, you'll absorb levothyroxine capsules and oral solution better than tablets. Capsules and oral solution are also less affected by over-the-counter and prescription drugs and supplements used to treat gastrointestinal and digestive conditions.


Research has also shown that you can take Tirosint® capsules and Tirosint®-SOL oral solution with breakfast, including coffee and milk, as well as with soy foods and fiber, with minimal impact on the absorption of the levothyroxine.


If you are taking a generic or brand name levothyroxine tablet, you should consider switching to Tirosint® when:

  • Your thyroid test levels are not stable on a consistent dosage of your current brand of levothyroxine tablet

  • Your thyroid test levels are optimal, but you don't feel well and continue to have symptoms on your current brand of levothyroxine tablet

  • You have signs or symptoms of allergies or sensitivity to excipients and/or dyes in your current brand of levothyroxine tablet

  • You are lactose-intolerant

  • You have seasonal allergies/hay fever

  • You are sensitive to iodine

  • You need to eat or drink coffee or milk at the same time as you take your levothyroxine

  • You eat a high-fiber diet

  • You eat a diet high in soy products


You should also consider Tirosint® if you take supplements or over-the-counter/prescription medications that interfere with tablet absorption. These include:

  • Iron

  • Calcium

  • Magnesium

  • Antacids that contain calcium, aluminum hydroxide and/or magnesium, such as Tums, Gaviscon, Maalox, and Mylanta

  • Proton pump inhibitors like Prilosec, Prevacid, and Nexium


You should also consider switching to Tirosint® capsules if you have a gastrointestinal or digestive condition that is known to affect levothyroxine tablet absorption, including:

  • Celiac disease

  • Inflammatory bowel disease/syndrome (IBD/IBS)

  • Ulcers and helicobacter pylori (H. pylori) infection

  • Gastrointestinal reflux disease (GERD)/acid reflux

  • Ulcerative colitis

  • Crohn's disease

  • Previous gastric bypass

  • Small intestinal bacterial overgrowth (SIBO)


The Tirosint®-SOL oral solution is recommended for infants and children being treated with levothyroxine for hypothyroidism, and for people who can’t swallow tablets or capsules.


How Much Does Levothyroxine Typically Cost?

If you have health insurance, your insurer categorizes prescription drugs in three tiers, each with its own copay rate or range. Tier 1 drugs are almost always generic and have the lowest copays. Tier 2 drugs are usually brand name drugs, and typically have somewhat higher copays for specific brands, designated by the insurance company as "preferred." Tier 3 drugs are non-preferred brand name drugs and carry the highest copays. 

I’ve put together the following graphic that shows the retail price range, as well as the tier level and typical insurance copays, for different brands and generic levothyroxine. I've also included the cost when you use manufacturer copay cards and programs, to give you an idea of how much you can potentially save. 


How Can You Save on Your Levothyroxine Prescription?

There are several key ways to save on the cost of your levothyroxine, and pay the lowest possible price:

  • Use Manufacturer Programs (Copay Cards, Discount Coupons, Direct Purchase, Patient Assistance Program)

  • Use Pharmacy/Grocery/Retailer Discount Programs

  • Use Outside Coupon and Discount Programs

  • Pay the Retail Price


Manufacturer Programs

  • Copay Cards are special discount cards offered by drug companies that provide a discount off your insurance copay for your drug.

  • Some manufacturers offer discount coupons that let you get a certain percentage off if you are uninsured.

  • Direct purchase programs let you order your medication from designated mail-order pharmacies to save on markups.

  • Patient Assistance Programs – known as PAPs – provide free or low-cost medication for people who qualify. Eligibility for PAPs is based on income and health insurance status.


Levoxyl®: How to Save

Synthroid®: How to Save

Tirosint® and Tirosint®-SOL: How to Save

Unithroid®: How to Save

Pharmacy / Grocery / Retailer Discount Programs

Pharmacies and retailers like CVS, Walgreens, Rite-Aid, Kroger, Publix, Meijer, Safeway, and others have programs you can join that provide discounts on medications. You can search for these discount programs at NeedyMeds:

Walmart stores also sell generic levothyroxine for $4 for a 30-day supply, with or without insurance.

And mail order pharmacy HoneyBee makes generic levothyroxine available for $8 for a 30-day supply, without insurance. You can find HoneyBee online at

Outside Coupon and Discount Programs

Several services offer a function for you to search for levothyroxine, compare prices, and find store and manufacturer copay cards, coupons, and discounts.  My recommended places to start your research include:

Pay Retail

Your insurance copay for levothyroxine is often MORE than the retail cash price. Various studies have shown that about half the people taking levothyroxine are paying copays that are HIGHER than the retail cash price without insurance!

You can’t assume that the pharmacy will tell you if you’re overpaying. In some states, it's actually illegal for pharmacists to volunteer this information!

ALWAYS to ask the pharmacist or staff to run your insurance copay price versus the retail price of the drug. If you ask, they’re required to tell you.

If the retail price is less, bypass your insurance and pay the cash price. That way YOU pocket the savings, instead of the pharmacy benefits manager or your health insurance company!


For a detailed look at all the ways you can save as much as hundreds of dollars a year on your levothyroxine, review Part 2 of the Levothyroxine Deep Dive Webinar: Saving on the Cost of Levothyroxine.


The Levothyroxine Deep Dive program is copyright © 2020, Mary Shomon. All rights reserved.

Levoxyl®, Synthroid®, Tirosint®, Tirosint-SOL®, and Unithroid® are registered trademarks. Product images and logos used with permission. 


Mary Shomon does not provide medical advice, diagnosis or treatment.


The contents of this video and material contained on the website ("content") are for informational purposes only. The content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have learned from this video or site.

If you think you may have a medical emergency, call your doctor or 911 immediately. Mary Shomon does not recommend or endorse any specific tests, physicians, products, procedures, opinions, or other information that may be mentioned. Reliance on any information provided by Mary Shomon is solely at your own risk.

bottom of page