Doctors prescribe Fosamax (alendronate) to treat osteoporosis, thinning of the bones that may lead to fractures. The drug works by slowing down the body's process of breaking down bone. Merck's marketing of the drug and its safety have faced scrutiny by critics and the FDA.

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Fosamax Pills

Dosage: 5 mg, 10 mg, 35 mg, or 70 mg

Used to Treat: Osteoporosis

Related Drugs: Boniva, Actonel, Aredia, Didronel, Reclast Skelid, Zometa

FDA Safety Communications: Potential risk for esophageal cancer, risk of thigh bone (femur) fractures, risk of atrial fibrillation

Active Ingredient: Alendronate sodium and cholecalciferol

FDA Approval: 1995, also available as Fosamax Plus D approved in 2005

View Lawsuit Information

About 10 million Americans have osteoporosis and about 44 million have low-bone density, putting them at risk of fractures. Fosamax (alendronate sodium) belongs to a drug class called bisphosphonates prescribed to treat osteoporosis — bone loss that occurs as people age. When bones get too thin, they become brittle and the risk of fracture increases. While osteoporosis is more common in women, men may also suffer from the condition. Biphosphonates work by slowing the body’s natural process of breaking down bone. This helps maintain or increase bone density.

Bone With and Without Osteoporosis
Normal bone vs. bone with osteoporosis

Introduced in 1995 by Merck, Fosamax was the first drug in its class. Experts hailed the drug as the superior treatment for people who have or are at risk for osteoporosis and Paget’s disease of bone, a disease that leads to misshapen bones.

In 2005, the U.S. Food and Drug Administration approved Fosamax Plus D (alendronate sodium and cholecalciferol). This formula combines the original active ingredient in Fosamax plus vitamin D. Vitamin D helps the body process calcium, a mineral needed to keep bones strong.

At the height of its popularity, the drug brought in billions in annual revenue for Merck. In 2008, Merck lost its patent, and the FDA approved the first generic version of Fosamax.

Fosamax is generally well-tolerated, and the most common side effects are irritation of the esophagus and stomach ulcers. But the drug is linked to some serious but rare side effects such as thigh fractures and jaw bone problems. Some studies also link the drug to a small risk of esophageal cancer, though the FDA has not issued a warning.

Merck also faced scrutiny for its controversial marketing practices of the drug. These included misleading ads, pushing bone-density machines on doctors and publishing fake journal articles.

How Does Fosamax Work?

As people get older, the body naturally breaks down more bone. This causes bones to become weaker and thinner. This process is called resorption. Fosamax treats bone loss by slowing the resorption process.

In clinical studies on animals, alendronate — Fosamax’s active ingredient — adhered to bones in rats and mice. Alendronate prevented resorption and new bone formed on top of the drug molecules, improving bone thickness. In order to keep slowing resorption and forming new bone, patients have to keep taking Fosamax.

Fosamax’s active ingredient — alendronate — slows the resorption process while new bone is formed on top of the drug molecules, improving bone thickness.

Researchers looked at biomarkers of bone resorption in urine of post-menopausal women taking 10 mg of Fosamax a day. By tracking these markers, researchers were able to gauge how effective the drug was. Study results showed a 50 to 70 percent reduction in resorption. These resorption levels were similar to those found in premenopausal women.

Even if patients won’t see or feel a difference, Fosamax and Fosamax D have been shown to improve bone density in as little as one month. The improvement plateaued at three to six months after starting treatment, according to the medication insert.

Studies show that Fosamax is effective at reducing the risk of spine, hip and wrist fractures in women with osteoporosis. According to an article published online in Harvard Health Publications, the drug can improve bone density for at least 10 years.

Fosamax Side Effects

According to the medication insert, Fosamax has been studied for safety in about 8,000 postmenopausal women. Researchers documented side effects from clinical trials. After the drug hit the market, researchers also received reports of additional side effects. The most commons side effects were gastrointestinal issues and esophageal irritation.

Side effects in clinical trials and post-marketing experience include:

  • Abdominal pain
  • Nausea
  • Constipation
  • Diarrhea
  • Flatulence
  • Acid regurgitation
  • Bone, muscle or joint pain
  • Headache
  • Dizziness and vertigo
  • Fatigue
  • Esophageal ulcer

Rare side effects include:

  • Allergic reactions
  • Skin rashes including Stevens-Johnson syndrome (blisters and peeling skin)
  • Hypocalcemia (too much calcium in the blood)
  • Peripheral edema (swelling)
  • Gastric or duodenal ulcers
  • Femur fractures
  • Dead Jaw Syndrome, also known as osteonecrosis (a condition characterized by swelling, infection and bone death in the jaw)
  • Esophageal erosion with bleeding
  • Esophageal perforation
  • Hypocalcemia (low blood calcium)

FDA Actions and Fosamax Safety Issues

The FDA released a number of safety communications for Fosamax and other drugs in the same class. Key studies also added to growing safety concerns.

  • 2004

    The FDA found that long-term Fosamax use was linked to osteonecrosis of the jaw, which causes the jawbone to deteriorate.

  • 2007

    The FDA announced that it was aware of data linking Fosamax and other drugs in the class to potential increased risk of atrial fibrillation.

  • 2007

    The American Society for Bone and Mineral Research connected Fosamax to osteonecrosis of the jaw.

  • 2008

    The FDA warned that bisphosphonates were linked to debilitating bone, muscle and joint pain.

  • 2009

    A study in the New England Journal of Medicine linked long-term Fosamax use to esophageal cancer.

  • 2009

    A Swedish study found risk of femur stress fracture was 50 times higher in women who took Fosamax or another bisphosphonate compared to women who did not take the drugs.

  • 2010

    The FDA required that Fosamax and other drugs in its class include warning labels about the increase risk of thighbone (femur) fractures.

  • 2011

    The FDA added a new warning label to the drug that states that the optimal duration of Fosamax use has not been determined. An FDA advisory committee wants the agency to limit the amount of time a patient uses the drug, but the group can’t agree on the time limit.

Dosages and Strengths

Fosamax, which comes in a pill and liquid form, can be taken once a week or once daily, depending on the treatment. Fosamax Plus D only comes in a weekly tablet form. Doctors will determine the individual dosage for each patient.

  • Fosamax dosage strengths:

    5 mg, 10 mg, 35 mg, 40 mg and 70 mg

  • Fosamax Plus D dosage strengths:

    70 mg/2800 and 70 mg/5600

Instructions for Taking Fosamax and Fosamax Plus D

There is a narrow set of parameters for taking Fosamax. These instructions are very important. Not taking Fosamax as directed could decrease the medicine’s effectiveness or increase adverse events.

Because Fosamax is most effective when taken on an empty stomach, the drug should be taken at least a half hour before eating breakfast with a full glass of water. Patients should not lie down for at least 30 minutes after taking the pill. They should not eat, drink or take any other medications within 30 minutes of taking it. Patients should not take Fosamax at bedtime or before getting up for the day.

Fosamax 10mg Pills
Fosamax 70mg Pills
Fosamax (10mg) should be taken once daily and Fosamax Plus D (70mg) should be taken once a week

According to the medication insert, the recommended starting dosages are one 10 mg tablet once daily or a 70 mg tablet or oral solution once weekly.

The recommended starting dose of Fosamax D is 70 mg alendronate/5600 international units vitamin D3 once weekly.

Who Should Not Take Fosamax or Fosamax Plus D?

Because of how Fosamax works and is metabolized by the body, there are certain people who should not take the drug. The drug is known to cause irritation to the gastrointestinal lining and may worsen underlying diseases, including Barrett’s esophagus, dysphagia and gastritis. Doctors should be cautious when prescribing Fosamax to patients with preexisting conditions. Fosamax and Fosamax Plus D are not approved for use in children.

People with the following condition should not use Fosamax:

  • People with abnormalities or problems related to the esophagus
  • People who cannot sit upright or stand for at least 30 minutes
  • People with hypocalcemia (low calcium in the blood)
  • People allergic to ingredients in Fosamax or Fosamax Plus D
  • People at increased risk of aspiration, a condition where food or liquid is breathed into the airways, should not take liquid Fosamax.

Fosamax Drug Interactions

Fosamax is known to interact with several common medications. Some make the drug less effective, while others can increase the risk of side effects.

Drugs that can negatively alter the effectiveness of Fosamax include:

  • Aspirin and NSAIDs drugs (ibuprofen, naproxen and anaprox) cause increased stomach irritation
  • Iron supplements and magnesium products prevent Fosamax absorption
  • Antacids makes Fosamax less effective

Fosamax Marketing Controversy

In July 1997, the FDA sent Merck a warning for falsely advertising the Fosamax’s benefits in a brochure targeting postmenopausal women. The agency said Merck overstated the benefits of the drug and minimized the risks. The FDA called the content of the ad “misleading and in violation of the Federal Food, Drug and Cosmetic Act.”

The ad stated, “Menopause is the single most important cause of osteoporosis.” According to the FDA, this statement is false and implies all women with menopause develop osteoporosis. The agency previously warned Merck of the same issues in December 1995 and April 1997, the letter states. FDA requested Merck immediately discontinue the use of the brochure and similar materials.

Creating a Market for Fosamax

In order to reach the millions at risk for osteoporosis, Merck opened its nonprofit Bone Research Institute to encourage physicians to do bone exams. With it, the company was not only able to reach the osteoporosis market, but also convinced medical professionals that osteopenia — lower bone density not severe enough to be considered osteoporosis — needed treatment as well. Before Fosamax, osteopenia was rarely diagnosed or treated because it doesn’t cause disabling bone breaks.

Critics say that Merck created a disease simply to sell more Fosamax.

It started in 1995, when the company hired Jeremy Allen, formerly of a massive pharmaceutical research company called IMS Health, to help them sell Fosamax. The drug giant hired Allen after its initial sales were poor, he told National Public Radio in 2009.

Bone Scan on a Computer
Merck boosted sales of Fosamax by motivating large numbers of women to have their bones scanned for osteoporosis

Allen’s solution was to get large numbers of women to get their bones scanned and be diagnosed with osteoporosis. The company then approached companies to fund the development of smaller, cheaper bone scanners that experts said should not be used to diagnose osteoporosis.

After the machines were ready, Merck funded trials to get the machines past FDA. Then, it sent out its sales team with information on the devices to doctors and created leasing programs to help doctors buy them. The pharma giant then lobbied for legislation called the Bone Mass Measurement Act to get Medicare to pay for the scans.

Fosamax sales soared into the billions within the next few years as a result of the bone scanners.

Fake Medical Journal to Sell Fosamax

Merck paid publisher Elsevier to produce a journal that looked like a peer-reviewed medical journal but was actually a marketing tool for Fosamax and other Merck products.

In 2009, The Scientist magazine reported that Merck paid publisher Elsevier to produce the Australasian Journal of Bone and Joint Medicine, which looked like a peer-reviewed medical journal. In reality, it was a marketing tool for Fosamax and other Merck products, including its then blockbuster pain reliever, Vioxx. The journals were published from 2003 to 2004.

Samples of the journal surfaced in a civil suit against Merck for Vioxx. It included only positive conclusions about the drugs. There were 12 articles dedicated to Fosamax. Many of the supposed articles had no authors and few references.

Elsevier admitted Merck had sponsored the publication and there were no disclosures to indicate it was sponsored by Merck. Critics said it was a ploy to trick doctors who might be influenced by the publication.

Please seek the advice of a medical professional before making health care decisions.


Michelle Y. Llamas is a senior content writer. She is also the host of Drugwatch Podcast where she interviews medical experts as well as patients affected by drugs and medical devices. She has written medical and legal content for several years — including an article in The Journal of Palliative Medicine and an academic book review for Nova Science Publishers. With Drugwatch, she has developed relationships with legal and medical professionals as well as with several patients and support groups. Prior to writing for Drugwatch, she spent several years as a legal assistant for a personal injury law firm in Orlando. She obtained her English – Technical Communication degree from the University of Central Florida. She is a committee member with the American Medical Writers Association.

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