Forteo® (teriparatide) is a FDA-approved medicine for treatment of osteoporosis in postmenopausal women, men, and individuals treated with steroids. Forteo is the only osteoporosis medicine that targets the bone building cells, osteoblasts. This is in contrast to all the other medicines that work by lowering the rate of bone breakdown and targeting the osteoclast.

How Forteo Works

Forteo made from a portion of human parathyroid hormone. Forteo causes an increase of your circulating parathyroid hormone for a short burst of time. This extra parathyroid hormone increases number, activity, and lifespan of osteoblasts. Since this process is not linked to bone breakdown activity by osteoclasts in bone remodeling cycle, new bone and connections are formed.

An Easy To Use Injection “Pen”

You give yourself a shot under the skin once a day. This is easier than it may sound. The medicine is contained in a pen-like device, so you don’t have to measure or draw up anything. The same amount of medicine is automatically injected for you. The pen lasts for 28 days. You store it in the refrigerator. Each day you use a new needle that is small and thin. You barely feel a prick with the automatic injector.


With about two years of use of Forteo in the Fracture Prevention Trial, the risk of fractures at the spine and nonspine sites dramatically decreased by 65% and 53%, respectively. Bone mineral density by DXA increased more at the spine (9.7%) then the total hip (2.6%). However, DXA results may underestimate the actual changes. Forteo increases bone size and improves bone microstructure. Since bone mineral density assessed DXA is two-dimensional rather than three-dimensional, the increase in bone size may cause a lower than actual increase in bone density. In addition, DXA scans are unable to assess changes in microstructure.


Forteo is limited to a total of two years of use. This limitation was made because of the length of the original fracture clinical trial was almost two years. In addition, some laboratory rats receiving high doses of Forteo developed a tumor of the bone called osteosarcoma. On approval of Forteo in 2002, a “black box warning” about laboratory rats developing osteosarcoma was included in the product label information. The manufacturer Eli Lilly and Company has a surveillance plan for capturing any cases of osteosarcoma. In over 10 years since approval, there has been no increased occurrence of osteosarcoma with use of Forteo.

Possible side effects include pain and joint aches, leg cramps and nausea. A transient increase in blood calcium occurs after the injection but usually stays within normal range.

Should You Consider Forteo?

Forteo may be a good choice for you if you have already had a fracture, particularly in your spine. If you have osteoporosis with lower bone density in you lumbar spine compared with your hip sites that put you at high risk for spine fractures. Also if you have not responded to other medicines or are stopping your osteoporosis medicine but are still are high-risk for fracture, Forteo may be appropriate next step.

After your two years of use of Forteo, you will need to choose another osteoporosis medicine to start in order to maintain the benefits achieved with Forteo.

Other Resources:

Forteo Product Website