Specifically, the Food and Drug Administration (FDA) has approved levothyroxine oral tablet for use in adults and children to:
- treat hypothyroidism (underactive thyroid)
- treat a certain type of thyroid cancer, together with surgery or radioactive iodine
This article describes possible side effects of levothyroxine oral tablet. You’ll also find information on cost savings and coupon options for levothyroxine. You can explore this overview article to learn more about levothyroxine oral tablet, including the drug’s uses, side effects, ways to save on cost, and more.
Levothyroxine oral tablet is a generic version of the brand-name drugs Synthroid, Unithroid, Levoxyl, and Thyro-tabs. Levothyroxine also comes in injectable forms and other oral forms, but these forms aren’t described in this article. To learn more about these forms, talk with your doctor.
Boxed warning: Not for weight loss or treatment of obesity
Levothyroxine has a boxed warning for the drug not to be prescribed for weight loss or the treatment of obesity. A boxed warning is the most serious warning from the FDA.
For details, see the “Warnings for levothyroxine” section below.
More common side effects of levothyroxine
Levothyroxine oral tablet may cause mild or serious side effects. Below are some of the more common side effects of this medication.
Commonly reported side effects of levothyroxine oral tablet include:
- fatigue (low energy)
- headache
- appetite changes
- weight loss or weight gain
It’s important to note that small changes in your levothyroxine dose may cause large changes in your thyroid hormone levels. This may cause side effects. Be sure to talk with your doctor about any side effects you have with levothyroxine. In some cases, your doctor may need to change your levothyroxine dosage.
Mild side effects of levothyroxine
Levothyroxine may cause certain mild side effects. Most often, mild side effects are temporary and can be easily managed. Tell your doctor or pharmacist if you have side effects that don’t go away or become bothersome.
Mild side effects of levothyroxine oral tablet that occurred in studies include:
- abdominal cramps
- diarrhea
- fatigue (low energy)
- feeling anxious or irritable
- headache
- sensitivity to hot weather or high temperature environments
- appetite changes
- weight loss or weight gain
- menstrual irregularity (irregular periods)
- muscle spasm
- nervousness
- sweating
- tremor (shaking)
- insomnia (difficulty sleeping)
- weakness
- vomiting
- hair loss*
- mild allergic reaction*
* To learn more about this side effect, see the “Side effects of levothyroxine in detail” section below.
Levothyroxine oral tablet may cause more mild side effects than those listed above. For details, see the drug’s prescribing information.
It’s important to note that small changes in your levothyroxine dose may cause large changes in your thyroid hormone levels. This may cause side effects. Be sure to talk with your doctor about any side effects you have with levothyroxine. In some cases, your doctor may need to change your levothyroxine dosage.
Serious side effects of levothyroxine
Levothyroxine may cause certain serious side effects. If you have any serious side effects from levothyroxine oral tablet, call your doctor right away. But if you think you’re having a medical emergency or your side effects feel life threatening, take immediate action. Call 911 or a local emergency number, or go to the nearest emergency room.
After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Visit MedWatch’s website if you’d like to notify the FDA about a side effect you’ve had with levothyroxine.
Serious side effects of levothyroxine oral tablet that occurred in studies include:
- mood swings
- seizures
- heart-related side effects*
- bone mineral density loss*
- severe allergic reaction*
It’s important to note that small changes in your levothyroxine dose may cause large changes in your thyroid hormone levels. This may cause side effects. Be sure to talk with your doctor about any side effects you have with levothyroxine. In some cases, your doctor may need to change your levothyroxine dosage.
* To learn more about this side effect, see the “Side effects of levothyroxine in detail” section below.
Common questions about side effects of levothyroxine
Here are answers to some common questions about side effects of levothyroxine oral tablet. If you have other questions, talk with your doctor or pharmacist.
Will levothyroxine 50 micrograms (mcg) cause fewer side effects than levothyroxine 100 mcg?
Possibly. In general, lower drug doses tend to cause fewer side effects compared with higher doses. However, this was not specifically noted in studies of levothyroxine.
Keep in mind that the dosing of levothyroxine your doctor prescribes is specific to you. Your doctor will prescribe the dosage that’s right for you based on your blood test results, weight, age, symptoms, and other factors. As these factors change over time, your doctor will likely change your dosage of levothyroxine as well.
Talk with your doctor or pharmacist to learn more about your risk of side effects based on your levothyroxine dose.
Are side effects of levothyroxine in females similar to those seen in males?
Yes, the side effects of levothyroxine are generally similar in females* and males.* However, if the dosage of levothyroxine is too high or too low, females may have menstrual irregularity (irregular periods).
Also, loss of bone mineral density (thinning bones) has been specifically reported in females who’ve gone through menopause. These females took higher dosages of levothyroxine than needed to manage their condition.
Your doctor will order blood tests to check your thyroid hormone levels throughout levothyroxine treatment. This allows your doctor to check whether your dosage is managing your condition effectively or whether it needs to be changed.
Talk with your doctor or pharmacist if you have questions about side effects in females with levothyroxine.
* Sex and gender exist on spectrums. In this article, we use the terms “female” and “male” to refer to a person’s sex assigned at birth.
Does levothyroxine cause long-term side effects?
No, long-term side effects aren’t expected with levothyroxine oral tablet. In studies, specific side effects weren’t seen in people who had taken the drug for a long time. Long lasting side effects after treatment ended also weren’t reported.
Talk with your doctor if you have questions about long-term side effects with levothyroxine.
Coupon for levothyroxine
Visit this page to access Optum Perks coupons and get price estimates for levothyroxine when you use the coupons. These coupons can provide significant savings on your prescription costs.
Note: Optum Perks coupons cannot be used with insurance copays or benefits.
Side effects of levothyroxine in detail
Below you’ll find details on some of the side effects of levothyroxine oral tablet.
Heart-related side effects
In studies, heart-related side effects were rare in people taking levothyroxine oral tablet. These side effects may be serious.
Specific heart-related side effects reported in these studies include:
Certain factors can increase the risk of heart-related side effects with levothyroxine oral tablet. These include:
- being age 65 years or older
- having an existing heart condition
- taking a levothyroxine dose higher than what’s recommended
- taking a levothyroxine dose higher than needed based on your current thyroid hormone levels
Ways to manage
Heart-related side effects caused by levothyroxine may be serious and require immediate treatment. If your symptoms feel life threatening, call 911 (or your local emergency number) or seek emergency medical help. Examples include trouble breathing and chest pain or discomfort, which may spread to your shoulder, arm, or back.
To help prevent heart-related side effects, it’s important to attend office visits with your doctor. It’s also important to get blood tests to check your thyroid hormone levels when your doctor orders them. The results of these tests help your doctor make necessary changes to your dosage. This is to make sure that you’re taking the amount that’s right for you.
Hair loss
In studies, hair loss was rare in people taking levothyroxine oral tablet. This side effect is usually mild.
With hair loss, you may lose hair on certain parts of your body. You may lose hair all over, or the hair loss may be partial. For example, your hair may thin but not go away completely. In other cases, hair may disappear from an area entirely.
Certain factors can increase the risk of hair loss with levothyroxine oral tablet. These include taking a levothyroxine dose that is higher than recommended.
Ways to manage
If you experience hair loss, tell your doctor. They’ll likely recommend lowering your levothyroxine dose. Or they may temporarily stop treatment to determine whether this eases your hair loss.
During treatment with levothyroxine, your doctor will sometimes order blood tests to check your thyroid hormone levels. Your doctor will determine your levothyroxine dosage in part based on the results of these tests. Hair loss may be a sign of high thyroid hormone levels, so your doctor may lower your levothyroxine dosage if you have hair loss.
Free prescription coupons
Seriously … free. Explore prices that beat the competition 70% of the time.
Get free cardBone mineral density loss
In studies, bone mineral density loss was rare in people taking levothyroxine oral tablet. This side effect may be serious.
With bone mineral density loss, your bones lose important minerals, including calcium. Calcium is the most important mineral for bone health. With this condition, you may not experience symptoms. But it increases your risk of broken bones, especially if it’s left untreated over time.
Certain factors can increase the risk of bone mineral density loss with levothyroxine oral tablet. These include:
- taking a dose of levothyroxine that’s too high for your current thyroid hormone levels
- having gone through menopause
Ways to manage
If you have concerns about bone mineral density loss, tell your doctor. They’ll likely review your risk factors for bone loss, including whether any medications you take may cause it. They may suggest a bone mineral density test to check for this side effect.
Your doctor will occasionally order blood tests to check your thyroid hormone levels. They’ll determine and change your levothyroxine dose based on these tests. Keeping your thyroid hormone levels in the usual range helps lower your risk of bone mineral density loss.
Allergic reaction
For some people, levothyroxine oral tablet can cause an allergic reaction.
Symptoms can be mild or serious, and they may include:
- itchiness
- skin rash
- swelling under the skin, usually affecting eyelids, lips, hands, or feet
- swelling of the mouth, tongue, or throat, which can make it hard to breathe
- flushing (temporary warmth, redness, or deepening of skin color)
Ways to manage
For mild allergic reaction symptoms, such as a mild rash, call your doctor right away. They may recommend treatments to help manage your symptoms. They’ll also let you know whether you should keep taking the medication.
For severe allergic reaction symptoms, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms require immediate medical care because they can become life threatening.
If you’ve had a serious allergic reaction to levothyroxine oral tablet, your doctor may recommend taking a different medication instead.
Warnings for levothyroxine
Below are some factors you may want to discuss with your doctor before taking levothyroxine oral tablet.
Boxed warning: Not for weight loss or treatment of obesity
Levothyroxine has a boxed warning for the drug not to be prescribed for weight loss or treatment of obesity. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).
Levothyroxine oral tablet should not be taken for weight loss or to treat obesity. In people with usual thyroid function, levothyroxine dosages for treating underactive thyroid are not effective for weight loss. And taking larger than recommended levothyroxine doses can lead to life threatening side effects, including heart attack. Taking levothyroxine with certain medications prescribed for weight loss, including phentermine, further raises your risk of these side effects.
Due to this risk, levothyroxine isn’t prescribed for weight loss or obesity treatment. Talk with your doctor if you have questions about your weight or strategies to manage it.
Other warnings
It may not be safe for you to take levothyroxine oral tablet if you have specific health conditions. These are sometimes called drug-condition interactions. Other things may also affect whether levothyroxine oral tablet is a safe treatment option for you.
Before taking levothyroxine oral tablet, tell your doctor about your health and medications you take. Things to consider include:
- adrenal insufficiency
- diabetes
- heart conditions, including irregular heart rhythm
- osteoporosis
- past allergic reaction to levothyroxine
Levothyroxine and pregnancy
In general, levothyroxine oral tablet is considered safe to take during pregnancy. That said, check with your doctor about whether they feel it’s safe for you specifically.
Levothyroxine and breastfeeding
In general, levothyroxine oral tablet is considered safe to take while breastfeeding. That said, check with your doctor about whether they feel it’s safe for you specifically.
Levothyroxine and alcohol
Levothyroxine oral tablet is not known to interact with alcohol.
That said, if you have certain side effects from levothyroxine, drinking alcohol could make them worse. Examples of these side effects include nervousness, sweating, and vomiting.
If you drink alcohol, talk with your doctor about whether it’s safe to consume it during your treatment with levothyroxine oral tablet.
What to ask your doctor
This article describes common and serious side effects of levothyroxine oral tablet. If your doctor prescribes this medication, they can discuss possible side effects with you. Let your doctor know if you have concerns or questions about treatment with this medication.
Here’s a list of some possible questions you may want to ask your doctor:
- If I have side effects from taking levothyroxine, can you prescribe a lower dosage for me?
- Does my health history affect my risk of side effects from taking levothyroxine?
- Do any medications I take interact with levothyroxine and raise my risk of side effects?
- Are there foods or diets I should avoid while taking levothyroxine?
Disclaimer: Optum Perks has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.