8 Forteo Side Effects You Should Know About

Forteo (teriparatide) is an FDA-approved osteoporosis medication that comes as a once-daily injection. It might be recommended if your fracture risk is very high. Forteo is a lab-made version of parathyroid hormone — a hormone in the body that helps build bone. And while it can be an effective option, it does carry a risk of side effects.

You may wonder why it makes sense to take a medication that might cause side effects when you feel fine or haven’t had a bone break. But keep in mind, osteoporosis fractures can lead to significant pain and loss of mobility. Your healthcare provider can help you weigh your risks to know if Forteo is right for you. 

Below, we’ll cover eight Forteo side effects and how to manage them.

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1. Head, joint, and body aches

Based on initial clinical studies, Forteo might cause various types of pain — body aches, headache, or joint pain. Joint pain had the strongest link to Forteo, with about 10% of people reporting it (versus 8% in the placebo group).

If you feel a bit achy after starting Forteo, know that it’s typically temporary. If your pain is mild, follow the steps that usually help you feel better when you experience aches or pains. Tips to try could include getting enough rest, applying heating or ice packs, or taking hot showers. You can also ask your provider or pharmacist if it’s OK for you to take an over-the-counter (OTC) pain reliever like acetaminophen (Tylenol).

Forteo is unlikely to cause severe or persistent pain. Let your healthcare provider know if you’re having a lot of pain or don’t feel better after a few days.

2. Digestive problems

Gastrointestinal (related to the stomach and intestines) side effects have been linked to Forteo in clinical studies. These could include stomach upset, nausea or vomiting, and diarrhea or constipation. These Forteo side effects might be related to shifting calcium blood levels.

When you first start Forteo, try to avoid foods that might bother your stomach, like fried or spicy foods. You can also try eating bland foods, such as toast or bananas, that are easier on the stomach. Staying well hydrated is important if you’re experiencing diarrhea or vomiting.

If you have digestive woes that persist — or are really bothersome — make sure to have them checked out by your healthcare provider. They can help you figure out if they’re related to Forteo and come up with a plan to address your specific issue.

3. Dizziness

You might feel dizzy after your first few Forteo injections. About 8% of people experienced this in clinical studies. It’s most noticeable when you first start the medication. It should lessen or resolve as your body gets used to it.

Dizziness could be a symptom of low blood pressure, another Forteo side effect. Low blood pressure is typically limited to the first 4 hours after a dose. Standing up quickly from a seated or lying position can worsen dizziness and low blood pressure. This is called orthostatic hypotension, and it can raise your risk of falls or fainting.

Consider these tips for staying safe:

• Plan your first few doses of Forteo in a place where you can sit or lie down quickly if you need to.

• Consider injecting doses at bedtime, so dizziness happens when you’re already lying in bed.

• Change positions slowly and have something safe and secure to grab onto nearby.

• Be mindful of your fluid intake during the day; dehydration can make dizziness worse.

If you experience dizziness after a Forteo injection, it should go away within a few hours. But if you’re still feeling dizzy when your next dose is due, talk with your healthcare provider before taking it.

4. Weakness or tiredness

After starting Forteo, some people feel a bit more weak or tired than usual. This side effect showed up in almost 9% of people during early clinical studies.

If you notice weakness or a lack of energy after starting Forteo, make sure you’re getting enough fluids during the day and enough sleep at night. Eating foods rich in calcium and vitamin D, getting regular exercise, and limiting alcohol are good for your bone health. But they might also help boost your energy.

Reach out to your healthcare provider if your energy levels don’t return to normal after a few weeks. Persistent weakness or tiredness can be a symptom of high calcium levels (more on that below).

5. Cold symptoms

If you find yourself grabbing for the tissue box after starting Forteo, it’s possible your runny nose is a side effect. Other cold symptoms — like sore throat and cough — were also reported in people taking Forteo during clinical studies.

If you notice some mild cold symptoms after starting Forteo, follow your usual get-better routines. Reach out to your healthcare provider if you’re still not feeling better after a week — or sooner if you start feeling worse.

6. Higher blood calcium levels

Forteo can cause your calcium blood level to go up — peaking about 4 to 6 hours after the injection — and then quickly drop back down to a normal range. For some people, these levels may stay higher for longer.

But overall, this Forteo side effect should be mild and temporary. Muscle weakness, tiredness, and nausea or vomiting are some symptoms of high calcium levels. However, there have been rare cases of calciphylaxis — a life-threatening condition caused by calcium deposits that block blood flow.

Your healthcare provider might recommend checking your calcium blood level during the first few months of treatment. Forteo isn’t recommended for people who have existing high blood calcium, or who have a health condition that might be worsened by high calcium levels. These include kidney stones, calcium skin deposits, and hyperparathyroidism.

7. Worsening of kidney stones

There’s no evidence that Forteo causes kidney stones. But there’s a risk that it could make existing kidney stones worse. If you’ve had kidney stones in the past, your healthcare provider may recommend tests to help them identify if you might be at risk for developing kidney stones. Or they may recommend a different osteoporosis medication that doesn’t raise calcium levels.

8. Possible risk for bone cancer

Forteo used to carry a boxed warning (the FDA’s most serious warning) for a possible risk of bone cancer. This was based on studies done in rats. But the rats were given very high Forteo doses for nearly a lifetime. Safety studies have found no evidence that Forteo causes bone cancer in humans.

In 2020, the FDA removed Forteo’s boxed warning. Newer long-term studies using real-world data didn’t find a link between Forteo and bone cancer in humans. But studying bone cancer is difficult because it’s a rare form of cancer. So more research is needed to say whether there’s no risk of bone cancer with Forteo.

Out of caution, Forteo’s manufacturer doesn’t recommend using it for more than 2 years to help limit risks. In some cases, your healthcare provider might still prescribe it to you based on your personal health history.

You shouldn’t take Forteo if you have Paget's disease (a rare bone condition that raises the risk of bone cancer). It’s also not recommended if you’ve had radiation treatment to your bones or have other health conditions that increase your risk for bone cancer.

When should I contact my healthcare provider about Forteo side effects?

Forteo is generally well tolerated. If you notice mild side effects, contact your healthcare provider if they’re bothersome or don’t get better. They can help you decide if continuing Forteo is right for you.

Serious Forteo side effects are rare but possible. Call 911 or get immediate medical care for any of the following:

• Severe nausea or vomiting

• Severe weakness or fainting

• Trouble breathing or chest pain

• Facial swelling or hives

Why trust our experts?

Written by:

Daphne Berryhill, RPh

Daphne Berryhill, RPh, has two decades of experience as a clinical pharmacist. She spent most of her career in the Chicago area practicing in-home infusion.

Edited by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

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