Short answer: In the label's two placebo-controlled trials, the most common Forteo side effects were pain (21.3% vs 20.5% on placebo), joint pain (10.1% vs 8.4%), rhinitis (9.6% vs 8.8%), weakness (8.7% vs 6.8%), nausea (8.5% vs 6.7%) and dizziness (8.0% vs 5.4%). The label also warns about allergic reactions, high blood calcium and dizziness on standing after early doses. There is no boxed warning.
What Forteo is approved for: Forteo is a parathyroid hormone analog (PTH 1-34) approved for postmenopausal women with osteoporosis at high risk for fracture, to increase bone mass in men with primary or hypogonadal osteoporosis at high risk for fracture, and for men and women with osteoporosis from long-term steroid (glucocorticoid) use at high risk for fracture, or for people who could not use or did not respond to other osteoporosis treatments (section 1).
Source
FORTEO (teriparatide) injection, for subcutaneous use, prescribing information and Medication Guide. Eli Lilly. DailyMed, version published August 19, 2026. DailyMed setid aae667c5-381f-4f92-93df-2ed6158d07b0
No. The current Forteo label has no boxed warning.
These are the label's own numbers from the Adverse Reactions section. Where the label compares with placebo (a dummy treatment), both columns are shown, so you can see how much more often a reaction happened on Forteo.
| Event Classification | Forteo N=691 (%) | Placebo N=691 (%) |
|---|---|---|
| Pain | 21.3 | 20.5 |
| Headache | 7.5 | 7.4 |
| Asthenia | 8.7 | 6.8 |
| Neck pain | 3.0 | 2.7 |
| Hypertension | 7.1 | 6.8 |
| Angina pectoris | 2.5 | 1.6 |
| Syncope | 2.6 | 1.4 |
| Nausea | 8.5 | 6.7 |
| Constipation | 5.4 | 4.5 |
| Diarrhea | 5.1 | 4.6 |
| Dyspepsia | 5.2 | 4.1 |
| Vomiting | 3.0 | 2.3 |
| Gastrointestinal disorder | 2.3 | 2.0 |
| Tooth disorder | 2.0 | 1.3 |
| Arthralgia | 10.1 | 8.4 |
| Leg cramps | 2.6 | 1.3 |
| Dizziness | 8.0 | 5.4 |
| Depression | 4.1 | 2.7 |
| Insomnia | 4.3 | 3.6 |
| Vertigo | 3.8 | 2.7 |
| Rhinitis | 9.6 | 8.8 |
| Cough increased | 6.4 | 5.5 |
| Pharyngitis | 5.5 | 4.8 |
| Dyspnea | 3.6 | 2.6 |
| Pneumonia | 3.9 | 3.3 |
| Rash | 4.9 | 4.5 |
| Sweating | 2.2 | 1.7 |
1,382 men and postmenopausal women aged 28 to 86, median 11 months (men) and 19 months (women) of treatment. Everyone also took 1000 mg calcium and at least 400 IU vitamin D a day. Serious adverse events were 16% on Forteo vs 19% on placebo.
Blood calcium rose for a few hours after each dose, peaking at about 4 to 6 hours. At least one episode of high calcium in that window happened in 11% of women and 6% of men on Forteo vs 2% and 0% on placebo; it was confirmed on repeat tests in 3% of women and 1% of men.
Uric acid rose above normal in 3% on Forteo vs 1% on placebo, without more gout, joint pain or kidney stones.
Steroid-induced osteoporosis trial (Forteo vs a daily oral bisphosphonate): nausea 14% vs 7%, gastritis 7% vs 3%, pneumonia 6% vs 3%, shortness of breath 6% vs 3%, insomnia 5% vs 1%, anxiety 4% vs 1%, shingles 3% vs 1%.
In short-term studies of healthy volunteers, 5% had brief dizziness or fainting feelings on standing, usually within 4 hours of a dose and gone within minutes to hours.
Two US claims-database studies found 3 osteosarcoma cases among 379,283 Forteo users and 0 among 153,316, suggesting a similar risk to comparison groups; the label says the data have limits.
Reported after approval: rare bone tumors and osteosarcoma, calcium above 13 mg/dL, allergic reactions including anaphylaxis, high uric acid, sudden shortness of breath, chest pain, leg or back muscle spasms, and injection site pain, swelling and bruising.
The Warnings and Precautions part of the label lists these. Each line gives the label's heading and what it means in plain words.
Allergic reactions. Anaphylaxis, angioedema and hives have been reported with parathyroid hormone analogs, including Forteo. If signs appear, Forteo is stopped, and it is stopped permanently after a severe reaction.
Osteosarcoma (bone cancer). Teriparatide caused osteosarcoma in rats, and cases have been reported in people after approval, though observational studies in humans have not shown a higher risk. Forteo is avoided in people with higher baseline risk: open growth plates, Paget's disease or other metabolic bone disease, bone cancer or metastases, past radiation to the skeleton, or inherited conditions that raise the risk.
High calcium and skin calcification. Forteo can cause or worsen high blood calcium and is avoided in people with an underlying high-calcium disorder such as primary hyperparathyroidism. Calciphylaxis and worsening skin calcification have been reported, and Forteo is stopped if they occur.
Kidney stones. Forteo has not been studied in people with active kidney stones. Urine calcium may be checked, and benefits and risks are weighed with active or recent stones.
Dizziness on standing. Brief drops in blood pressure on standing can happen with the first several doses, so the first doses are given where the person can sit or lie down.
Digoxin. Because Forteo briefly raises blood calcium, people taking digoxin are watched for signs of digitalis toxicity.
Who should not use it. People with a history of severe allergy to teriparatide or any of Forteo's inactive ingredients.
From the Medication Guide that comes with Forteo:
Dose Track has a side-effect log. Each entry records the symptom, a severity (none, mild, moderate, severe or life-threatening), the date and an optional note, and can be tied to a specific dose or logged on its own. The history screen shows what you logged over time, which makes it easier to tell your prescriber when a reaction started and whether it is easing. The app records what you enter; it does not judge whether a symptom is serious. For anything on the label's call-your-doctor list, call your doctor.
This page is what the FDA label says, in plain words. It is not medical advice. Follow your prescriber, and ask them or your pharmacist about anything here.