Side Effects of Forteo: What You Need to Know

If you have a certain kind of bone condition, your doctor might suggest Forteo as a treatment option. It’s a prescription drug with the following uses in adults:

• treating osteoporosis in females* who have gone through menopause and are at high risk of bone fractures
• increasing bone mass in males* with certain kinds of osteoporosis and high risk of bone fractures
• treating osteoporosis in adults who have a high risk of bone fractures due to long-term use of glucocorticoids such as prednisone (Rayos)

The active ingredient in Forteo is teriparatide. (An active ingredient is what makes a drug work.) It comes as a liquid solution that you inject under your skin.

If you and your doctor determine that Forteo is safe and effective for you, you’ll likely use it long term. But using Forteo for longer than 2 years is not recommended.

For more information about Forteo, including details about its uses, see this in-depth article.

Like other drugs, Forteo can cause mild to serious side effects, also referred to as adverse effects. Keep reading to learn more.

* In this article, we use the terms “male” and “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article. (There’s ongoing research about the risk of osteoporosis in transgender individuals. But it’s not known how hormone or surgical transitions may affect their risk of osteoporosis. For more information, talk with your doctor.)

Some people may experience mild to serious side effects during their Forteo treatment. Examples of the drug’s commonly reported side effects include:

* To learn more about this side effect, see the “Side effects explained” section below.

Many of Forteo’s side effects are mild and go away after a few days to weeks. Examples of mild side effects that have been reported with this drug include:

• nausea
• body pain
• headache
• dizziness
• trouble sleeping
• diarrhea
• constipation
• runny nose
• sore throat
• indigestion (upset stomach)
• skin rash
• teeth-related side effects*
• injection site reactions*
• joint pain*
• mild allergic reaction*

* To learn more about this side effect, see the “Side effects explained” section below.

In most cases, these side effects should be temporary. And some may be easily managed. But if you have symptoms that are ongoing or bother you, talk with your doctor or pharmacist. And do not stop using Forteo unless your doctor recommends it.

Forteo may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

Some people may have serious side effects while using Forteo. But, in many cases, these are rare.

Serious side effects that have been reported with this drug include:

• sudden decrease in blood pressure when you sit up or stand
• chest pain
• fainting
• depression
• serious infections, such as pneumonia or shingles
• high blood calcium level
• osteosarcoma*
• severe allergic reaction†

If you develop serious side effects while using Forteo, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

* To learn more about this side effect, see the “Side effects explained” section below.
† An allergic reaction is possible after using Forteo. But it’s not clear whether this side effect occurred in studies.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Forteo, visit MedWatch.

Get answers to some frequently asked questions about Forteo’s side effects.

Are weight gain and hair loss side effects of Forteo?

No, these side effects aren’t likely with Forteo. Weight changes, including weight loss or weight gain, were not reported as side effects in this drug’s studies. Hair loss was also not reported with this medication.

Keep in mind that this drug is used to treat osteoporosis due to the long-term use of corticosteroids such as prednisone (Rayos). It’s possible that these medications may cause weight gain.

Also, a decrease in certain hormone levels can lead to osteoporosis. In some cases, lower hormone levels may cause hair loss. So you may have hair loss due to decreased hormone levels and not as a side effect of Forteo.

Talk with your doctor if you have concerns about weight changes or hair loss with this drug.

Does Forteo cause any long-term side effects?

It’s possible to have long-term side effects from Forteo. Long-term side effects include those that continue for a long time while you’re using the medication or after you stop treatment. Or they may start after you’ve been using Forteo for a long time or after your treatment ends.

A kind of bone cancer called osteosarcoma is a possible long-term side effect of Forteo. To learn more, see the “Side effects explained” section below.

Will suddenly stopping Forteo cause withdrawal symptoms?

No, Forteo is not known to cause withdrawal symptoms after stopping treatment. Withdrawal symptoms are side effects that may happen after you stop using a medication your body has become dependent on.

Note that stopping Forteo may cause your osteoporosis to worsen if you don’t start a different treatment for it. Be sure to talk with your doctor before stopping this drug. They can recommend a different treatment for your condition.

Learn more about some of the side effects Forteo may cause.

Teeth-related side effects

Teeth-related side effects are possible but not common while using Forteo. Tooth disorder was reported as a rare side effect in the drug’s studies. But it’s not clear which specific dental side effects occurred.

Joint pain is a common side effect of Forteo. If you have joint pain in your jaw, it may feel like tooth pain.

It’s important to note that Prolia (denosumab), another drug used to treat osteoporosis, may cause osteonecrosis of the jaw. This is a rare side effect that may result in tooth loss. But this side effect wasn’t reported in Forteo studies.

What might help

It’s important to maintain healthy oral hygiene during your Forteo treatment. This may help minimize teeth-related side effects.

Let your doctor know if you experience any tooth discomfort while using Forteo. They can examine your teeth or refer you to a dentist to determine the cause of your symptoms.

If you have concerns about teeth-related side effects with Forteo, talk with your doctor.

Injection site reactions

It’s possible to have injection side effects while using Forteo, but these weren’t reported in the drug’s studies. However, people who used Forteo after the drug became available on the market did report having injection site reactions. These include reactions at or near the injection site, such as:

What might help

Injection side effects with Forteo are usually mild and go away on their own. If you have injection site reactions, applying an ice pack to the site following the injection may help relieve pain and swelling. Rotating the site where you inject Forteo each time can also help avoid injection site reactions. (Forteo may be injected into the abdomen or thighs.)

Let your doctor know if you have very painful or bothersome injection side effects while using Forteo. They can discuss injection techniques with you to help prevent these side effects.

Your doctor may also recommend that you take over-the-counter (OTC) pain relievers, such as acetaminophen (Tylenol) or ibuprofen (Advil, Motrin). But always talk with your doctor or pharmacist before taking any OTC drugs. They’ll let you know whether these drugs are safe for you to take.

Osteosarcoma (a kind of bone cancer)

It’s possible to develop osteosarcoma (a kind of bone cancer) while using Forteo. This side effect wasn’t reported in the drug’s studies but was reported by people taking the drug after it came on the market. Symptoms of osteosarcoma can include:

• bone pain that doesn’t go away
• swelling
• unusual lumps on your body

Some people have a higher risk of osteosarcoma if they use Forteo, including:

• children* and young adults with bones that are still growing
• people with certain bone conditions, such as Paget’s disease of the bone
• people with cancer that has spread to their bones
• people who have had light or radiation therapies that affect the bones

* Forteo is not approved for use in children.

What might help

Tell your doctor if you have any conditions that may increase your risk of osteosarcoma. They’ll likely recommend a treatment other than Forteo for you. You should also let them know if you have symptoms of osteosarcoma during your Forteo treatment. They’ll determine the cause of your symptoms and decide whether it’s safe for you to continue using this drug.

To reduce the risk of osteosarcoma, your doctor will likely not prescribe Forteo for longer than 2 years.

Joint pain

Using Forteo can cause joint pain. This was one of the more common side effects reported in the drug’s studies. Joint pain with Forteo is usually mild and goes away after a few days to weeks.

What might help

Let your doctor know if you have bothersome joint pain during your Forteo treatment. They may recommend over-the-counter (OTC) pain relievers, such as acetaminophen (Tylenol) or ibuprofen (Motrin, Advil).

Always talk with your doctor or pharmacist before taking any OTC medications. They can tell you whether they’re safe to take with Forteo or your condition.

Allergic reaction

Like most drugs, Forteo can cause an allergic reaction in some people. But it’s not clear whether this side effect occurred in studies. Symptoms can be mild to serious and can include:

• skin rash
• itchiness
• flushing (temporary warmth, redness, or deepening of skin color)
• swelling under your skin, usually in your eyelids, lips, hands, or feet
• swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. Examples include:

• an antihistamine you swallow, such as Benadryl (diphenhydramine)
• a product you apply to your skin, such as hydrocortisone cream

If your doctor confirms you’ve had a mild allergic reaction to Forteo, they’ll decide whether you should continue using it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to Forteo, they may have you switch to a different treatment.

• what dose of the drug you were taking when you had the side effect
• how soon you had the side effect after starting that dose
• what your symptoms were
• how it affected your daily activities
• what other medications you were taking
• any other information you feel is important

Forteo may not be right for you if you have certain medical conditions. This is known as a drug-condition interaction. Other factors may also affect whether Forteo is a good treatment option for you. Talk with your doctor about your health history before starting this drug. Factors to consider include those described below.

Increased risk of osteosarcoma. Forteo may increase your risk of osteosarcoma. This risk is even higher if you have other risk factors for this condition, such as:

• bones that are still growing
• certain bone conditions, such as Paget’s disease of the bone
• cancer that has spread to your bones
• previous light or radiation therapies that affect the bones

Let your doctor know if you have any of these risk factors before starting Forteo. They’ll recommend a different treatment for your condition.

Allergic reaction. If you’ve had an allergic reaction to Forteo or any of its ingredients, your doctor will likely not prescribe it for you. Ask them about other medications that might be better options.

Kidney stones. Forteo may increase your blood calcium levels. This can increase your risk of developing kidney stones. If you already have this condition, Forteo may worsen it. Tell your doctor if you’ve had kidney stones in the past. They may monitor your blood calcium level closely during your Forteo treatment.

High blood calcium level. Using Forteo may increase your blood calcium level. If you have other conditions that increase your blood calcium level, such as hyperparathyroidism, Forteo may worsen them. Let your doctor know if you have conditions that increase your blood calcium level before starting this drug. They’ll likely recommend a different treatment for your condition.

Alcohol and Forteo

There are no known interactions between Forteo and alcohol. But Forteo can cause a sudden decrease in blood pressure as you stand or sit up. This can happen up to 4 hours after you inject the drug.

With a sudden decrease in blood pressure, you may have symptoms such as dizziness and lightheadedness. Drinking alcohol can also cause these symptoms, which may worsen the side effects of Forteo and increase your risk of falling.

Drinking large amounts of alcohol can also increase your risk of osteoporosis, which Forteo is used to treat.

If you drink alcohol, talk with your doctor about how much, if any, is safe to consume while using Forteo.

Pregnancy and breastfeeding with Forteo

It’s not known whether it’s safe to use Forteo during pregnancy. There haven’t been any studies done on pregnant people using this medication. This drug is usually prescribed to people who can’t become pregnant, such as females* who have gone through menopause, and males.*

If you’re pregnant or planning to become pregnant, talk with your doctor before starting Forteo. They’ll likely recommend a different treatment for your osteoporosis.

You should not use Forteo while breastfeeding. It’s not known whether the drug passes into breast milk or what effect it would have on a child who’s breastfed.

If you’re breastfeeding or planning to do so, talk with your doctor before starting Forteo. They can recommend safe ways to feed your child while you’re using this medication.

* In this article, we use the terms “male” and “female” to refer to someone’s sex assigned at birth. For information about the difference between sex and gender, see this article.

Forteo may cause mild to serious side effects. If you have questions about the side effects this drug can cause, talk with your doctor. Getting answers to some of your questions can help you learn what to expect and how to manage any side effects. Here are a few questions to start with:

• How do the side effects of Forteo compare with those of Prolia?
• Is my risk of joint pain higher when I first start treatment?
• Am I at higher risk of side effects if I have kidney problems?

To learn more about Forteo, see these articles:

• Forteo (teriparatide)
• Forteo and Cost: What You Need to Know

To get information on different conditions and tips for improving your health, subscribe to any of Austra Health’s newsletters. You may also want to check out the online communities at Bezzy. It’s a place where people with certain conditions can find support and connect with others.

Disclaimer: Austra Health 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.

Last medically reviewed on April 4, 2023