Forteo side effects and how to avoid them

Forteo is a brand-name medication that is manufactured by Eli Lilly and Company. It is classified as a parathyroid hormone (PTH) analog, which means it works like PTH your body makes naturally and is used to treat osteoporosis (bone loss). While Forteo is generally well tolerated, there are some potential side effects that people should be aware of. The most common side effects of Forteo include leg cramps and joint pain. Less common but more serious side effects can include severe allergic reactions.

Learn more about the side effects of Forteo and what you can do to avoid them.

What is Forteo (teriparatide)?

Forteo is a medication prescribed to adults to treat osteoporosis. Specifically, it’s given to:

  • Postmenopausal women with osteoporosis who have a high risk of bone fractures
  • Men with primary osteoporosis or hypogonadal osteoporosis who have a high risk of bone fractures
  • Men and women with osteoporosis caused by glucocorticoid medicines, like prednisone, who have a high risk of bone fractures

Osteoporosis can be treated with a range of medications, but most treatments only prevent you from losing more bone mass. Forteo can go a step further and help you rebuild lost bone. It can help increase your bone mineral density, giving you harder bones that are less likely to fracture.

The active ingredient in Forteo is called teriparatide. It’s a hormone your body naturally produces that promotes bone growth. When you take Forteo, the teriparatide it contains encourages your body to make more calcium and phosphate available for bone production. It also stimulates two types of cells, called osteoblasts and osteoclasts, that help produce new bone material increasing your bone density and strength.

Forteo dosage

Forteo is available in injection form in the following doses: 250 mcg/mL in single-use prefilled pens containing daily doses of 20 mcg.

Forteo is injected under your skin (subcutaneous injection) using a self-injecting, pre-filled Forteo delivery device. Your doctor may prescribe additional calcium and vitamin D supplements to help your bones get stronger.

You are advised to read the prescribing information and medication guide provided with this medicine for the drug information and patient information, and always speak with your healthcare provider for medical advice about any changes to your dose so they can monitor and evaluate your condition.

Forteo side effects

The most common side effects of Forteo include:

  • Injection site reactions
  • Nausea
  • Leg cramps
  • Joint pain

In rare instances, you could experience more serious long-term side effects. These can include:

  • Severe allergic reactions – chest pain, discomfort, tightness, trouble breathing, or heaviness
  • A fall in blood pressure (hypotension) when you change positions that can cause dizziness, lightheadedness, a fast heartbeat, and fainting
  • Increased risk of osteosarcoma (a type of bone cancer)
  • An increase in blood calcium levels (hypercalcemia) – nausea, vomiting, constipation, tiredness, and muscle weakness

If you experience any of these serious side effects, stop taking Forteo and seek medical attention immediately. You are encouraged to report the negative side effects of prescription drugs to the FDA. Visit, or call 1-800-FDA-1088.

Does Forteo cause weight gain?

Weight gain or weight loss is not a side effect of using Forteo. Speak to your doctor if you experience this side effect.

Does Forteo cause hair loss?

Hair loss is not a side effect of Forteo. Speak to your doctor for medical advice if you experience this side effect.

Does Forteo cause cancer?

Bone cancer has been seen in animal studies with rats and rarely in humans. Speak to your doctor immediately if you experience bone pain, a tender lump or any other swelling under the skin.

Can Forteo cause kidney damage?

Forteo may cause an increase in calcium levels in the blood. High calcium loss through the kidneys may cause kidney stones.

How long do Forteo side effects last?

Common side effects such as dizziness or a fast heartbeat may continue for a few minutes to a couple of hours. This side effect may go away as your body adjusts to Forteo.

Forteo drug interactions

Forteo can interact with other medications, including:

  • Medications that contain digoxin which can change how Forteo and the other medications work

Before taking Forteo, be sure to tell your doctor about all of the medications you are taking to ensure they are safe to take at the same time.

Forteo warnings & precautions

Don’t take Forteo if you:

  • Are allergic to the active ingredient teriparatide or any of the other ingredients in Forteo
  • Have already taken Forteo for over two years (you shouldn’t take Forteo for more than two years over your lifetime)
  • Are under 18 years of age

Talk to your doctor before you use Forteo if you:

  • Have a bone disease, like Paget’s disease
  • Have any type of bone cancer
  • Are a young adult and your bones are still growing
  • Have, or have had kidney stones
  • Have, or have had, too much calcium in your blood
  • Have had radiation therapy
  • Will have problems injecting yourself and don’t have someone who can help you
  • Are pregnant or are planning to become pregnant
  • Are breastfeeding or are planning to breastfeed – It is not known if this medication passes into breast milk

You should always check with your doctor or pharmacist before taking any medication, including Forteo, to make sure it is safe for you.

What happens when you stop taking Forteo?

Once treatment is stopped with Forteo, any gains in bone density will be lost. You may be prescribed treatments such as Fosamax after stopping treatment with Forteo from maintaining your bone mineral density.

How to avoid Forteo side effects

The best way to avoid side effects is to take Forteo as directed by your doctor. Follow your doctor’s instructions carefully, and do not take more or less than prescribed.

If you experience any side effects, talk to your doctor or pharmacist. They may be able to recommend ways to help reduce or prevent some of the side effects.

1. Stick to the recommended dosage

Take your prescribed dose of Forteo that has been recommended by your healthcare professional. Do not take more or less than prescribed.

2. Monitor your blood sugar levels

If you have diabetes, it is important to monitor your blood sugar levels closely while taking Forteo. Check your blood sugar levels as directed by your doctor and report any changes to your doctor immediately.

3. Drink plenty of fluids

Drink eight to 10 glasses of water or fluids every day to help prevent dehydration, which can make side effects worse.

4. Avoid alcohol

Alcohol is not likely to interact with teriparatide or parathyroid hormone. High alcohol consumption is, however, a known risk factor for osteoporosis. Moderate alcohol consumption is advised when being treated for osteoporosis.

5. Don’t skip meals

Eating regular meals and snacks will help to prevent low blood sugar levels (hypoglycemia).

6. Check your feet

If you have diabetes, check your feet for any cuts, sores, or redness regularly. Tell your doctor if you experience problems with your feet while taking Forteo.

7. Know the signs and symptoms of Forteo side effects

Signs and symptoms of side effects include leg cramps and joint pain. If you experience these symptoms, speak to your doctor for medical advice.

8. Tell your doctor about all medications you’re taking

Be sure to tell your doctor about all other medications you’re taking, including over-the-counter drugs, vitamins, and herbal supplements, as they can interact with Forteo.

9. Get regular medical checkups

It is important to get regular medical checkups and monitor your medical conditions. Your doctor will monitor your side effects and may adjust your dose of Forteo as needed.

Medically reviewed

A medical professional has reviewed this article.

Jamie Winn, PharmD
Jamie Winn, PharmD

Jamie Winn, PharmD

Medical Writer & Reviewer

Jamie Winn, PharmD

Medical Writer & Reviewer

Dr. Jamie Winn received his Doctor of Pharmacy in 2002 from the University of South Carolina College of Pharmacy, Columbia, SC. Jamie is a medical reviewer for NiceRx.

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The content on this website is intended for information purposes only. It does not constitute medical advice. The information on this website should not be relied upon and is not a substitute for professional medical advice. You should always speak to your doctor regarding the risks and benefits of any treatment.