Is It Safe to Take Fosamax to Treat Osteoporosis?

Every drug has side effects and risks, and this is no less true for the drug Fosamax (alendonic acid) prescribed for the treatment of osteoporosis. Despite its effectiveness, there are some rare but potentially serious side effects associated with Fosamax, including femur (thigh bone) fractures and osteonecrosis of the jaw (jaw bone deterioration ).

This article explains what risks Fosamax poses, both common and rare, and how the risks are managed for people prescribed this drug.

What Is Fosamax?

Along with Actonel (risedronate) and Reclast (zoledronic acid), Fosamax (alendronate) belongs to a class of drugs called bisphosphonates used for the prevention and treatment of osteoporosis. Of the three, Fosamax is the most commonly prescribed.

Fosamax is also indicated for the treatment of Paget's disease of bone.

Bisphosphonates work by preventing the breakdown of bones and increasing bone density. They also decrease the risk of spine and hip fractures.

Common Side Effects

Fosamax was licensed for use in the United States in 1995 and is approved for use in both females and males with osteoporosis as well as people diagnosed with Paget's disease of bone.

The most common side effects involve the digestive tract, with symptoms ranging from mild to severe. With that said, only around 4% of users report significant side effects. Of these, roughly one in 10 will stop treatment due to drug intolerability.

Common side effects of Fosamax include:

• Heartburn
• Upset stomach
• Stomach pain
• Nausea
• Diarrhea
• Constipation
• Bloating
• Gas
• Headache
• Bone, muscle, or joint pain
• Loss of taste or smell
• Dizziness

Many of these side effects subside or disappear as your body adjusts to the medication.

Rare Side Effects

The U.S. Food and Drug Administration (FDA) has documented potentially severe side effects of Fosamax and has issued several warnings highlighting both the short- and long-term risks. These include such rare side effects as bloody stools, difficulty swallowing, skin blisters, eye pain, and chest pain.

Ironically, the side effects most concerning to the FDA are those associated with bone demineralization (loss of bone mineral) and osteonecrosis (bone tissue death).

Studies showed that over the short term calcium in the blood decreases by about 2% in the first month of using Fosamax. To mitigate the risk, calcium and vitamin D supplements are commonly prescribed along with the drug.

Over the longer term, Fosamax and the other bisphosphonates are linked to more serious concerns, most notably an increased risk of:

• Osteonecrosis of the jaw (ONJ) caused by decreased blood flow to bone cells of the jaw
• Atypical femur fractures associated with bisphosphonate use that typically occur in the middle of the thigh bone

To reduce the risk, the American Association of Clinical Endocrinologists (AACE) and the American College of Endocrinology (ACE) recommend that females at moderate risk for osteoporosis take a "drug holiday" from bisphosphonates after five years of oral use. Females at high risk are advised to take a drug holiday after 10 years of oral use.

A 2018 study in Endocrine Practice questioned whether this practice is suitable for all people. According to the researchers, as many as 9.9% of females who took a drug break experienced a fracture within six years of stopping the drug. Most cases occurred within the fourth or fifth years.

These fractures, referred to as pathologic fractures, were thought to be due to bone mineral loss that occurred after treatment was stopped.

What to Do

As worrisome as the warnings might seem, it is important to put things into perspective and weigh the benefits and risks of any drugs you take.

Among the considerations, it's important to note that the risk of atypical femur fracture is low, affecting anywhere from three to 50 of every 100,000 Fosamax users per year. Even rarer is the risk of ONJ, affecting fewer than two of every 100,000 bisphosphonate users per year.

In contrast, Fosamax use is associated with as much as a 50% reduction in the risk of hip fractures in people with osteoporosis.

To this end, it's important to have your condition regularly monitored if you are prescribed Fosamax. Most experts recommend a follow-up appointment every six months.

If a drug holiday is recommended, you should still continue to see your provider for follow-up appointments, getting regular blood tests, bone scans, and bone density tests when recommended. If the risk of bone fracture is low following a three- to five-year drug holiday, some treaters will stop Fosamax permanently.

In the meantime, healthy lifestyle practices including regular exercise and weight loss are advised along with a diet rich in calcium and vitamin D.