Forteo is a brand-name injection that’s prescribed for osteoporosis. Forteo contains the active drug teriparatide and belongs to the parathyroid hormone (PTH) analog drug class.

Forteo is FDA-approved to:

* Sex and gender exist on spectrums. Use of the terms “female” and “male” in this article refers to sex assigned at birth.

Drug details

You’ll find key information about Forteo below.

  • Drug form: solution given as a subcutaneous injection using a prefilled pen
  • Generic available? Yes
  • Prescription required? Yes
  • Year of FDA approval: 1987

Forteo is a brand-name drug that contains the active drug teriparatide. In Europe and other countries, teriparatide is classified as a biologic, but it is not considered to be a biologic in the United States. The Food and Drug Administration (FDA) defines a biologic as a drug made from living cells. A non-biologic or generic drug, on the other hand, refers to drugs made from chemicals.

In the U.S., Forteo is available in a generic form called teriparatide injection.* A generic drug is an exact copy of the active drug in a brand-name medication. They tend to cost less than brand-name drugs.

In Europe, a biosimilar to Forteo is available as Terrosa. A biosimilar medication is a drug that’s similar to a brand-name biologic drug. Biosimilars are just as safe and effective as the drug they are based on. And like generics, biosimilars tend to cost less than brand-name medications.

If you’re interested in using alternatives to Forteo, talk with your doctor.

* Bonsity is an FDA-approved alternative to Forteo. However, even though Bonsity was approved in late 2019, the drug is not yet available on the market.

Forteo can cause mild or serious side effects. The following lists contain some of the key side effects that may occur while taking Forteo. These lists do not include all possible side effects.

For more information about the possible side effects of Forteo, talk with your doctor or pharmacist. They can give you tips on how to manage any side effects that may concern or bother you.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you would like to notify the FDA about a side effect you’ve had with Forteo, you can do so through MedWatch.

Mild side effects

Below is a partial list of mild side effects of Forteo. To learn about other mild side effects, talk with your doctor or pharmacist or view Forteo’s prescribing information.

Mild side effects of Forteo can include:

Most of these side effects may go away within a few days or a couple of weeks. But if they become more severe or don’t go away, talk with your doctor or pharmacist.

* For more information about allergic reaction and Forteo, see “Allergic reaction” below.

Serious side effects

Serious side effects from Forteo are uncommon, but they can occur. Call your doctor right away if you have serious side effects. Call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

Serious side effects and their symptoms can include:

  • Increased calcium levels in your blood. Symptoms can include:
  • Kidney or bladder stones. Symptoms can include:
    • pain or pressure in your lower back or abdomen
    • painful or more frequent urination
    • nausea or vomiting
  • Serious infections, such as pneumonia or herpes zoster (shingles). Symptoms vary with different types of infection but may include:
    • fever or chills
  • Orthostatic hypotension (low blood pressure after you stand up quickly). This may lead to fainting after a dose of Forteo, especially after your first dose. Symptoms can include:
    • dizziness
    • feeling lightheaded
  • Shortness of breath. Symptoms can include:
    • feeling like you can’t breathe or take a deep breath
    • chest tightness
  • Possible increased risk* of osteosarcoma (a form of bone cancer). Symptoms can include:
    • pain in a certain area that gets worse over time
    • swelling in the affected area
    • weight loss
  • Calciphylaxis (buildup of calcium in the blood vessels of your skin). Symptoms can include:
    • painful skin lesions (abnormal-looking areas) that may be discolored
    • body aches
    • fatigue
    • weakness
  • Severe allergic reaction (see below).

You can also refer to this article for details about Forteo’s side effects.

* Osteosarcoma wasn’t reported in Forteo’s clinical trials but has been reported by people taking the drug after it came on the market. There is limited data available about the risk of osteosarcoma after using Forteo for more than 2 years.

Allergic reaction

As with most drugs, some people can have an allergic reaction after taking Forteo. It isn’t clear how often allergic reactions occurred among people who took the drug in clinical trials.

Symptoms of a mild allergic reaction can include:

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include:

  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your tongue, mouth, or throat
  • trouble breathing
  • hives

Call your doctor right away if you have an allergic reaction to Forteo, as the reaction could become severe. Call 911 or your local emergency number if your symptoms feel life threatening or if you think you’re having a medical emergency.

Other drugs are available that can treat osteoporosis. Some may be a better fit for you than others. If you’re interested in finding an alternative to Forteo, talk with your doctor. They can tell you about other medications that may work well for you.

The following drugs are similar to Forteo:

As with all medications, the cost of Forteo can vary. The actual price you’ll pay (including how much Forteo will cost per month) depends on your insurance plan, where you live, and the pharmacy you use.

Financial and insurance assistance: If you need financial support to pay for Forteo or need help understanding your insurance coverage, savings and support options are available. For Forteo, these include a co-pay card and a patient assistance program. For more information and to find out if you’re eligible for support, visit the Forteo’s manufacturer website.

To learn more about saving money on prescriptions with coupons and other options, check out this article.

Generic version: Forteo is available in a generic form called teriparatide injection. A generic drug is an exact copy of the active drug in a brand-name medication. The generic is considered to be as safe and effective as the original drug. And generics tend to cost less than brand-name drugs. To find out how the cost of teriparatide compares to the cost of Forteo, talk with your doctor or pharmacist.

The following information describes dosages that are commonly used or recommended. However, be sure to take the injection dosage your doctor prescribes for you. Your doctor will determine the best dosage to fit your needs.

Drug forms and strengths

Forteo comes as a solution in a prefilled pen. It’s given as a subcutaneous injection.

The strength of each injected Forteo dose is 20 micrograms (mcg) of teriparatide. The Forteo pen contains 28 doses for a total of 600 mcg per 2.4 milliliters (mcg/mL) of liquid solution. Each milliliter of liquid solution contains 250 mcg of teriparatide.

Dosage for osteoporosis

Forteo’s recommended dosage is one 20-mcg injection per day.

You can refer to this article for details about Forteo’s dosage.

How to inject

A healthcare professional will show you or your caregiver how to inject Forteo. The injections are given in your thigh or abdomen. You should change the area where you inject each dose so that you don’t use the exact same spot each day.

Forteo’s manufacturer provides a user manual with step-by-step instructions for storing and injecting the drug. They also offer Forteo Connect, a program that provides one-on-one injection training and support.

About using Forteo

Below you’ll find information about key dosage issues.

  • When to take: You should take your daily dose of Forteo at about the same time each day. This will help keep a consistent amount of the drug in your body. It’s a good idea to plan your dose for when you’ll be able to sit or lie down. After a dose of Forteo, it’s possible to develop dizziness or a fast heartbeat. This is more common with the first few doses after you start treatment.
  • If you miss a dose: If you miss a dose of Forteo, you should skip the missed dose. You should not inject more than one dose of Forteo on the same day. Doing so may increase your risk of side effects.
  • Length of use: Taking Forteo for more than 2 years may not be recommended due to the possible risk of osteosarcoma (a form of bone cancer) with Forteo. It’s best to talk with your doctor about how long you’ll continue your Forteo treatment.
  • Length of time to work: Forteo starts working soon after you inject your first dose. Most likely, you won’t notice Forteo working in your body. To monitor how well Forteo is working for you, your doctor will use a bone mineral density (BMD) test. In clinical trials, Forteo significantly increased BMD after 3 months of treatment in some people.


Using more than the recommended dosage of Forteo can lead to serious side effects. Do not use more Forteo than your doctor recommends.

Forteo comes as a prefilled pen that contains 28 doses of the drug. Some people have accidentally received an overdose by mistakenly injecting all of the medication in the pen at once. Be sure to only inject one dose per day. Follow your doctor’s instructions on how to inject your dose, or see Forteo’s user manual.

Overdose symptoms

Symptoms of an overdose can include:

What to do in case of overdose

If you think you’ve taken too much of this drug, call your doctor. You can also call America’s Poison Centers at 800-222-1222 or use its online tool. However, if your symptoms are severe, call 911 or your local emergency number, or go to the nearest emergency room right away.

The Food and Drug Administration (FDA) approves prescription drugs such as Forteo to treat certain conditions. Forteo may also be prescribed off-label for other conditions. Off-label drug use means prescribing a drug for a purpose other than what it’s been approved for by the FDA.

Forteo for osteoporosis

Forteo is FDA-approved to treat osteoporosis in adults who either have a high risk of bone fractures, cannot take other osteoporosis treatments, or have tried other treatments that did not work. Specifically, Forteo is used to:

  • treat osteoporosis in certain females* who’ve gone through menopause
  • increase bone mass in certain males* with some kinds† of osteoporosis
  • treat osteoporosis related to long-term use of glucocorticoids (a type of steroid medication), such as prednisone (this condition is also called glucocorticoid-induced osteoporosis)

Doctors may recommend daily calcium and vitamin D supplements for people with osteoporosis. If your doctor recommends these supplements for you, you can continue taking them during your Forteo treatment, according to your doctor’s instructions.

* Sex and gender exist on spectrums. Use of the terms “female” and “male” in this article refers to sex assigned at birth.
† Forteo is approved for use in males with primary osteoporosis or hypogonadal osteoporosis. Primary osteoporosis is typically related to older age. Hypogonadal osteoporosis is usually caused by low testosterone levels.

Forteo and children

Forteo isn’t approved for use in children because their bones are still growing.

Here are answers to some frequently asked questions about Forteo.

Will I have weight gain or weight loss with Forteo?

You should not expect to lose or gain weight as a side effect of taking Forteo. People taking the drug in clinical trials did not report weight changes.

But it’s possible that weight loss can occur due to a higher calcium level in your blood, a less common side effect of Forteo. Symptoms of increased calcium levels can include nausea, vomiting, constipation, fatigue, and muscle weakness. It’s possible that these symptoms can lead to some weight loss.

If you notice these symptoms or weight changes while using Forteo, talk with your doctor. They may check your calcium level with a blood test.

What’s the recommended duration of therapy with Forteo?

Forteo’s recommended duration of therapy is typically up to 2 years. But you and your doctor may decide you’ll take the drug longer, depending on your risk of bone fractures.

In animal trials, some rats treated with Forteo developed osteosarcoma (a form of bone cancer). Human trials have not shown an increased risk of osteosarcoma. However, in these trials, the drug was only used for up to 2 years. So it isn’t known if Forteo could increase the risk of osteosarcoma after 2 years of treatment. Since Forteo was approved for use, no increased risk of osteosarcoma has been found in people taking the drug.

Due to the possible risk of osteosarcoma, if your risk of bone fractures is low after 2 years of Forteo treatment, your doctor may have you stop taking Forteo. If your doctor determines that you’re still at high risk of fractures, they may recommend continuing Forteo treatment for more than 2 years.

It’s best to talk with your doctor about other options to treat your osteoporosis after 2 years of treatment with Forteo. They can give you more information on whether the benefits of continued Forteo treatment outweigh your risks for developing osteosarcoma.

Can I abruptly stop taking Forteo?

If you and your doctor decide that you’ll stop taking Forteo, you can stop it abruptly. Forteo does not cause withdrawal symptoms, and your body doesn’t become dependent on the drug.

Withdrawal symptoms are side effects that can happen when you stop taking a drug that your body has become dependent on. Drug dependence occurs when your body needs a drug to feel like it usually does.

However, your osteoporosis may worsen if you stop using Forteo and don’t start a different osteoporosis treatment. If your doctor suggests stopping Forteo, they’ll likely discuss a new treatment plan with you.

If you can become pregnant, consider the following information about pregnancy, birth control, and breastfeeding.

Forteo and pregnancy

It’s not known whether Forteo should be used during pregnancy. If you’re pregnant, planning a pregnancy, or can become pregnant, talk with your doctor before using this medication.

Forteo and breastfeeding

It’s not known whether Forteo is safe to use while breastfeeding. The manufacturer of the drug does not recommend breastfeeding while using Forteo, however.

If you’re currently breastfeeding or planning to do so, talk with your doctor before using this medication.

Before taking Forteo, talk with your doctor and pharmacist. Tell them about all prescription, over-the-counter, and other drugs you take. Also tell them about any vitamins, herbs, and supplements you use. Sharing this information can help you avoid potential interactions.

Medication interaction

A drug interaction has been reported in people who took Forteo with digoxin. Digoxin is a medication that treats heart problems such as atrial fibrillation (A-fib). Taking Forteo can temporarily increase your blood calcium level, which can increase the risk of side effects from digoxin.

This article does not contain all drugs that may interact with Forteo. If you have questions about drug interactions that may affect you, ask your doctor or pharmacist.

Alcohol interaction

Alcohol is not known to interact with Forteo. But it’s a good idea to limit alcohol use while taking Forteo. This is because some people develop orthostatic hypotension during their Forteo treatment.

Orthostatic hypotension can occur up to 4 hours after taking your dose, and symptoms include dizziness, lightheadedness, or fast heartbeat. These symptoms can happen when you stand up quickly. Drinking alcohol can also cause or worsen dizziness, which may lead to falling and getting injured.

Excessive alcohol use can raise your risk of osteoporosis and bone fractures, and Forteo is often used to treat osteoporosis in people who have a high risk of bone fracture. So it’s important to consider that drinking large amounts of alcohol could further increase your risk of a bone fracture.

If you have questions about drinking alcohol while using Forteo, talk with your doctor or pharmacist.

Before taking Forteo, discuss your health history with your doctor. Forteo may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

Note: For more information about the potential negative effects of Forteo, see the “Forteo side effects” section above.

Disclaimer: Medical News Today 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.

Forteo Images