Fosamax (alendronate)

Medically Reviewed By Heather Bruce, PharmD

About Fosamax

Fosamax is a brand-name prescription medication. It’s approved by the Food and Drug Administration (FDA) for the following uses in adults:

Fosamax has certain limitations of use. For details about these conditions and how the drug treats them, see the “Fosamax: Uses” section below.

* Sex and gender exist on spectrums. In this article, use of the term “female” refers to sex assigned at birth.

Key points

The following table provides key facts about Fosamax.

Active drugalendronate
Drug classbisphosphonate
Formoral tablet

Finding a healthcare professional

If you’re interested in taking this drug, search here to find a doctor who might prescribe it.

Fosamax: Generic

Fosamax is a brand-name medication. It contains the active drug alendronate, which also comes in a generic form. A generic is an identical copy of the active drug found in a brand-name medication.

The Food and Drug Administration (FDA) ensures that generic drugs are as safe and effective as their original drug. Generics tend to be less expensive than brand-name drugs.

Like Fosamax, generic alendronate comes as tablets that you swallow. However, generic alendronate is also available as an oral solution. (Fosamax used to come in this form, but it’s no longer available in the United States.)

If you’d like to know about the generic version of Fosamax, ask your doctor or pharmacist. They can tell you if the generic medication comes in forms and strengths recommended for your condition.

Fosamax: Side effects

As with most drugs, it’s possible to have side effects with Fosamax. These can include some mild side effects but also some serious ones.

To learn more about Fosamax’s side effects, talk with your doctor or pharmacist. They may also provide information about managing certain side effects of this drug.

Note: The Food and Drug Administration (FDA) tracks side effects of drugs it has approved. If you would like to notify the FDA about a side effect you’ve had with Fosamax, you can do so through MedWatch.

Mild and serious side effects

Mild and serious side effects of Fosamax are listed below. This article does not include all of Fosamax’s possible side effects.

Mild side effects

Mild side effects* of Fosamax may include:

Most times, mild side effects of a drug go away within a few days or a couple of weeks. Talk with your doctor or pharmacist if any side effects become severe or don’t go away.

* This is not a complete list of Fosamax’s mild side effects. To learn about other mild side effects of this drug, ask your doctor or pharmacist. Or you can view the drug’s prescribing information.
† To learn more about allergic reaction, see below. An allergic reaction is possible after taking Fosamax. However, this side effect wasn’t reported in clinical studies.

Serious side effects

Serious side effects of Fosamax may include:

  • effects on your esophagus, including esophagitis (inflammation in your esophagus), ulcers that may bleed, erosion, narrowing, or holes
  • damage to your jaw, including jaw osteonecrosis (death of jawbone tissue)
  • atypical femur fracture
  • hypocalcemia (low blood calcium level)
  • severe bone, joint, or muscle pain
  • severe allergic reaction*

Serious side effects from Fosamax aren’t common, but they are possible. If you have serious side effects, call your doctor right away. However, if you’re having a medical emergency or your symptoms feel life threatening, call 911 or a local emergency number.

* To learn more about allergic reaction, see below. An allergic reaction is possible after taking Fosamax. However, this side effect wasn’t reported in clinical studies.

Allergic reaction

As with most drugs, some people can have an allergic reaction after taking Fosamax. A more severe allergic reaction is rare but possible.

Allergic reactions weren’t reported in clinical studies, but they have happened since Fosamax was approved for use.

Possible symptoms of mild and serious allergic reactions are listed in the table below.

Mild allergic reaction symptomsSerious allergic reaction symptoms
flushing• swelling under your skin, possibly in your hands, feet, lips, or eyelids
rash• swelling in your throat or mouth
• itchingtrouble breathing

If you have an allergic reaction to Fosamax, call your doctor right away. This is important because the reaction could become severe.

However, if you’re having a medical emergency or your symptoms feel life threatening, call 911 or a local emergency number.

Fosamax: Dosage

Below, you’ll find dosages that are commonly recommended for Fosamax. However, you should take the dosage your doctor prescribes for you. They’ll recommend the dosage that’s best for your needs.

The dosage of Fosamax that your doctor prescribes will depend on the condition you’re using Fosamax to treat and the severity of the condition.

Fosamax’s forms and strengths

Fosamax is available as follows.

  • Form: oral tablet
  • Strength: 70 milligrams (mg)

Fosamax’s recommended dosages

Recommended dosages for Fosamax in adults are described below.

Note: Fosamax is no longer available in 5 mg, 10 mg, 35 mg, and 40 mg strengths. However, its generic form, alendronate, is still available in these strengths.

Adult dosage

The recommended dosage for Fosamax in adults is as follows.

PurposeRecommended Dosages
treating osteoporosis• 70 mg once per week or,
• 10 mg once per day
treating osteoporosis caused by glucocorticoids*• 5 mg once per day
preventing osteoporosis in postmenopausal females†• 35 mg once per week or,
• 5 mg once per day
treating Paget’s disease of bone• 40 mg once per day

* For this use, your doctor may recommend a different dosage. For example, in postmenopausal females not receiving estrogen, the recommended dosage is 10 mg once per day. Talk with your doctor to learn more.
Sex and gender exist on spectrums. In this article, use of the term “female” refers to sex assigned at birth.

Dosage considerations

Below are some things to consider about Fosamax’s dosage.

  • Missing a dose. If you miss a dose of Fosamax, try to take it as soon as you remember. However, if it’s nearly time for your next dose, skip the missed dose and take your next dose as usual. Do not take more than one dose of Fosamax at once. Try these medication reminder options to help avoid missing doses. You could also set an alarm, use a timer, or download a reminder app on your phone.
  • Length of treatment. Doctors may prescribe Fosamax as a long-term treatment for preventing or treating osteoporosis. However, it may also be used for shorter periods of time for this use. To learn more, see the “Fosamax: Uses” section below. For example, when used for Paget’s disease of bone, Fosamax is typically prescribed for 6 months. After that, your doctor can tell you more about whether you’ll need another treatment course.

Fosamax: Alternatives

Doctors may prescribe drugs other than Fosamax for your condition. Certain drugs may work better for you than others.

Fosamax is used to treat osteoporosis and other conditions. Here’s a summary of other drugs that doctors sometimes prescribe for osteoporosis.

To learn more about some alternatives to Fosamax, view the following articles:

Your doctor can tell you about other similar drugs, such as zoledronic acid (Reclast).

For additional information about alternatives to Fosamax, ask your doctor. They can tell you about other medications that could be prescribed for your condition.

Fosamax: Uses

Prescription drugs, such as Fosamax, are approved by the Food and Drug Administration (FDA) to treat certain conditions.

Using Fosamax for osteoporosis

Fosamax may be used for both preventing and treating osteoporosis.

Osteoporosis is caused by a decrease in your bone mineral density (BMD). It happens when your body reabsorbs more bone tissue than it produces to replace it.

Throughout your life, your bones are constantly reabsorbed and replaced. Cells, such as osteoclasts and osteoblasts, carry out these tasks. (Osteoclasts break down bone, while osteoblasts rebuild bone.) Your body breaks down and rebuilds your bones continuously in order to keep them strong.

However, in some people, bone starts to break down faster than new bone can form. Fosamax works to prevent or treat osteoporosis by stopping osteoclasts from breaking down bone. This allows your body’s osteoblasts to rebuild your bones and maintain their strength.

Note: Sex and gender exist on spectrums. In this article, use of the terms “male” and “female” refers to sex assigned at birth.

Using Fosamax to treat osteoporosis

Fosamax may be prescribed to treat osteoporosis in males and postmenopausal females.

Fosamax may also be prescribed to treat osteoporosis that is caused by using medications called corticosteroids, such as prednisone (Rayos).

Using Fosamax to prevent osteoporosis

Fosamax may be prescribed to prevent osteoporosis in postmenopausal females.

Limitations of use

For treating or preventing osteoporosis, clinical studies of Fosamax only looked at the drug when used for up to 4 years. Whether it’s safe or effective to continue taking Fosamax beyond this length of time is unknown.

If you’re at low risk for bone fractures, your doctor may suggest stopping Fosamax treatment after 3 years. Ultimately, you and your doctor will work together to determine how long you’ll continue taking Fosamax.

Using Fosamax for treating Paget’s disease of bone

Fosamax may be prescribed to treat Paget’s disease of bone.

With Paget’s disease of bone, the body breaks down and rebuilds bone very quickly. This results in softer, weaker bones that are more prone to fractures. The bones may also become enlarged or misshapen.

For treating Paget’s disease of bone, treatment with Fosamax typically lasts 6 months. At least 6 months after taking your last dose, your doctor may recommend re-treating your Paget’s disease of bone with Fosamax. Talk with your doctor for more information on re-treating Paget’s disease of bone with Fosamax.

Taking Fosamax with other therapies

Your doctor may suggest taking a vitamin D or calcium supplement while you’re taking Fosamax. This may depend on a few factors, such as your age and how much calcium you’re getting from your diet.

Calcium and vitamin D play important roles in maintaining healthy bones. Talk with your doctor about whether they recommend taking a vitamin D or calcium supplement in combination with Fosamax.

Using Fosamax in children

Fosamax is not approved for use in children. Talk with your child’s doctor if you’re seeking treatment for Paget’s disease of bone in children. Osteoporosis, Fosamax’s other use, typically doesn’t occur in children.

Finding a healthcare professional for Fosamax

If you’re interested in taking Fosamax, search here to find a doctor who might prescribe it. It may be helpful to check out this osteoporosis appointment guide to help prepare for your appointment.

Fosamax: Questions you may have

Here are some common questions about Fosamax and brief answers to them. If you’d like to know more about these topics, ask your doctor.

How long does it take for Fosamax’s side effects to go away?

It depends. Fosamax can affect each person differently. How long its side effects affect you may be different from someone else using the drug.

Most often, side effects caused by Fosamax are mild and go away on their own within a few days. However, some of the drug’s serious side effects, such as jaw osteonecrosis, may require treatment or cause long-term complications. (Jaw osteonecrosis is the death of bone tissue in the jaw.) However, serious side effects with Fosamax are rare.

Talk with your pharmacist or doctor if you have additional questions about how long it may take for Fosamax’s side effects to go away.

Can I stop taking Fosamax ‘cold turkey’? How should I stop taking Fosamax?

You shouldn’t stop Fosamax “cold turkey” without talking with your doctor first. It’s important to discuss with your doctor why you’re interested in stopping Fosamax (or any medication). If your doctor agrees that stopping Fosamax is safe for you, they can also review possible other treatments for your condition.

Stopping Fosamax isn’t expected to cause withdrawal symptoms. (Withdrawal symptoms are side effects that can occur when you stop taking a drug that your body has become dependent on.)

If you’re interested in stopping treatment with Fosamax, talk with your doctor. They can recommend the best way for you to stop taking the drug. They can also suggest other treatments for your condition.

Does Fosamax cause weight gain?

No, Fosamax isn’t expected to cause weight gain. This side effect wasn’t reported in the drug’s clinical studies.

Fosamax doesn’t work by adding bone mass to your body. Instead, the drug works to stop osteoclasts from breaking down your bones. (Osteoclasts are cells that break down bone.) To learn more about how Fosamax works, see the “Fosamax: How it works” section below.

If you have additional questions or concerns about your weight and medications you take, talk with your pharmacist or doctor.

Is Fosamax safe to take?

In general, yes. Fosamax has been reviewed by the Food and Drug Administration (FDA), which approves medications for treating certain conditions. The FDA weighs the risks and benefits of a drug before deciding whether to approve it.

Like most medications, Fosamax can cause side effects. In most cases, these are mild. However, the drug can cause serious side effects in rare instances. To learn more, see the “Fosamax: Side effects” section above. You can also view the drug’s prescribing information, or talk with your doctor or pharmacist, to learn more about the side effects Fosamax may cause.

Fosamax: How to take

Your doctor will recommend how you should take Fosamax. It’s important to take the drug exactly as your doctor instructs.

Fosamax comes as a tablet. You’ll take the drug by swallowing it.

There are important steps to follow each time you take a dose of Fosamax. Following these steps will help Fosamax work and lower your risk for side effects. These steps are discussed just below, under “Questions about taking Fosamax.”

After taking each Fosamax dose, it’s very important that you remain upright for at least 30 minutes and until you’ve eaten your first meal. However, it’s important to note that you’ll need to wait for at least 30 minutes before eating after you take a dose.

Questions about taking Fosamax

Here’s a list of common questions related to taking Fosamax.

  • When should I take Fosamax? Take Fosamax first thing upon waking up for the day. Fosamax should be taken with a full glass of water at least 30 minutes before eating or drinking anything except plain water, or before taking any other medications. Do not take Fosamax before going to sleep. You must remain upright for at least 30 minutes after taking a dose.
  • Do I need to take Fosamax with food? No. It’s actually very important that you do not take Fosamax with food. You’ll need to wait for at least 30 minutes before eating after you take a dose.
  • Can Fosamax be chewed, split, or crushed? No, it’s very important that you don’t chew, split, or crush Fosamax tablets. If you’re having trouble swallowing pills, talk with your doctor about switching to Fosamax’s generic oral solution. (To learn more about this, see the “Fosamax: Generic” section above.)
  • Is there a best time of day to take Fosamax? Yes, it’s important to take Fosamax first thing upon waking for the day. Fosamax should be taken with a full glass of water at least 30 minutes before eating or drinking anything except water, or before taking any other medications. Do not take Fosamax before bedtime. You must remain upright for at least 30 minutes after taking a dose.

Fosamax: Precautions

Tell your doctor about your health history before starting treatment with Fosamax. Your doctor may not recommend this medication if you have certain factors affecting your health or specific medical conditions. These situations are considered drug-condition interactions.

These factors and conditions include those listed below.

  • Contraindications to Fosamax. A contraindication is a factor or condition that could prevent your doctor from prescribing a drug due to risk of harm. Due to the risk, doctors typically will not prescribe Fosamax if you have:
    • problems with your esophagus that cause it to empty slower than usual, such as esophageal stricture
    • an inability to stand or sit upright for at least 30 minutes
    • hypocalcemia (low blood calcium level)
  • Scheduled dental work. It’s very important that you let your doctor know if you have dental work, including a tooth extraction or dental surgery, scheduled before you begin taking Fosamax. If performed while you’re taking Fosamax, certain dental procedures can raise your risk for jaw osteonecrosis (death of jawbone tissue). This is a rare but serious side effect Fosamax may cause. Your doctor may want to wait to prescribe Fosamax until after your dental work. If you need to have dental work or surgery while taking Fosamax, your doctor may temporarily pause your treatment to help lower your risk for jaw osteonecrosis.
  • Kidney problems. Using Fosamax isn’t recommended if you have severe kidney problems, such as severe chronic kidney disease (CKD). Your body relies on your kidneys to get rid of Fosamax after you take a dose. If you have a severe kidney problem, your body may not be able to get rid of Fosamax as well. This can raise your risk for side effects from the medication. People with mild or moderate kidney problems are usually safe to take Fosamax. However, it’s important to talk with your doctor first. They can offer more information on whether Fosamax is safe for you.
  • Trouble absorbing minerals in your stomach or gut (malabsorption syndrome). Sometimes, doctors recommend taking a vitamin D or calcium supplement (or both) in combination with Fosamax. However, if you have malabsorption syndrome, you may need higher doses of these supplements. Be sure to let your doctor know if you have malabsorption syndrome before you begin taking Fosamax. If they suggest using calcium or vitamin D supplements, this will help them recommend the right dose for you.
  • Allergic reaction. Your doctor will likely not prescribe Fosamax if you’ve had an allergic reaction to it or any of its ingredients. To find out about other treatment options, talk with your doctor.
  • Pregnancy. If you’d like additional information about taking Fosamax while pregnant, view the “Fosamax: Taking while pregnant” section above.
  • Breastfeeding. If you’d like additional information about taking Fosamax while breastfeeding, view the “Fosamax: Taking while breastfeeding” section above.

To learn more about effects of Fosamax that could be harmful, see the “Fosamax: Side effects” section above.

Fosamax: Cost

As with other medications, prices for Fosamax may vary. The drug’s price will depend on factors such as:

Cost considerations for Fosamax

Here are some things to consider when looking into the cost of Fosamax.

Option for a 90-day supply. For some drugs, it’s possible to get a 90-day supply. If this option is approved by your insurance company, it can help lower the cost of the drug. It can also help you avoid frequent trips to your pharmacy. If you’d like to learn more about this option, ask your doctor, pharmacist, or insurance company.

Need for prior authorization. Before insurance coverage for Fosamax is approved, your insurance company may require prior authorization. In this case, your doctor and insurance company will communicate about your prescription for Fosamax. Then, the insurance company will decide if the drug will be covered. To find out if you need prior authorization for Fosamax, contact your insurance company.

Possible cost assistance options. Financial assistance to help lower the cost of Fosamax may be available. To learn more and see if you’re eligible for support, visit Medicine Assistance Tool’s website. Also, check out this article to learn about ways to save on prescription drugs.

Use of a mail-order pharmacy. Fosamax may be dispensed through mail-order pharmacies. Getting your prescription through a mail-order pharmacy could lower its cost. It can also allow you to get the drug without leaving home. To find out more about this option, check with your doctor, pharmacist, or insurance company.

Availability of a generic form. Fosamax comes in a generic form called alendronate. A generic drug is an exact copy of the active drug in a brand-name medication. Generics are typically less expensive than brand-name drugs. If your doctor prescribes Fosamax, but you want to know about taking alendronate, talk with them about which option might be better for you. Also, check your insurance plan because it might cover just one form or the other.

Fosamax: How it works

Fosamax is used to prevent and treat osteoporosis. It’s also prescribed to treat Paget’s disease of bone. For more information about these conditions, see “Fosamax: Uses” section above.

About osteoporosis

Osteoporosis is caused by a decrease in your bone mineral density (BMD). It happens when your body reabsorbs more bone tissue than it produces to replace it.

Your bones are continuously reabsorbed and replaced throughout your life. These actions are carried out by cells such as osteoclasts and osteoblasts. (Osteoclasts break down bone and osteoblasts rebuild bone.)

In some people, the bone starts to break down faster than new bone can form. This may happen as people age, or it may be caused by taking certain medications that affect bone health. These medications may include corticosteroids, such as prednisone (Rayos).

About Paget’s disease of bone

With Paget’s disease of bone, the body breaks down and rebuilds bone very quickly. This results in softer, weaker bones that are more prone to fractures. The bones may also become enlarged or misshapen.

How Fosamax works

Fosamax works to prevent or treat osteoporosis by stopping osteoclasts from breaking down bone. This allows your osteoblasts to rebuild your bones and maintain their strength.

How long does Fosamax take to start working?

Fosamax begins working as soon as you take a dose. However, you won’t “feel” Fosamax working. Instead, your doctor will monitor your BMD using lab or imaging tests, such as a DEXA scan. Your doctor can provide more information about how they’ll monitor how well Fosamax is working for you.

Fosamax: Consuming alcohol during treatment

There’s no known interaction between taking Fosamax and consuming alcohol.

However, clinical studies have found consuming excessive amounts of alcohol to be a risk factor for developing osteoporosis. Fosamax is prescribed to treat and prevent this condition.

Additionally, consuming alcohol can also raise your risk for certain side effects Fosamax may cause. Some examples include:

If you drink alcohol, talk with your doctor about how much, if any, is safe for you to consume while taking Fosamax.

Fosamax: Interactions

Fosamax may interact with other medications, certain supplements, and certain foods.

Different interactions can cause different effects. Some interactions can interfere with a drug’s effectiveness. Others can increase a drug’s side effects or cause them to be severe.

Before you start Fosamax, be sure to tell your doctor about any medications, herbs, vitamins, or supplements you take. They can check for any possible interactions between these products and Fosamax.

After taking your Fosamax dose, it’s important to wait at least 30 minutes before taking any other medications and before eating or drinking anything except plain water. For more information, see “Fosamax: How to take” section above

If any of the interactions listed below might pertain to you, talk with your doctor. They can tell you what you need to do to avoid the interaction.

  • Fosamax and certain other medications. Because Fosamax may interact with the following drugs, your doctor may recommend you do not take it with these drugs. Examples include:
  • Fosamax and herbs and supplements. Fosamax may interact with calcium or magnesium supplements or supplements containing calcium or magnesium. It’s typically OK to use these supplements, but you should wait at least 30 minutes after taking your Fosamax dose before taking any supplement with calcium or magnesium.
  • Fosamax and foods. There aren’t any interactions known between Fosamax and foods. However, the drug should not be taken with food. For more information, see the “Fosamax: How to take” section above.

For information about drug-condition interactions, see the “Fosamax: Precautions” section above.

Fosamax: Taking while pregnant

It isn’t known whether it’s safe to take Fosamax while pregnant.

However, the drug’s manufacturer recommends that you stop taking Fosamax if you become pregnant during treatment.

Talk with your doctor before you start taking Fosamax if you are pregnant or planning a pregnancy.

Fosamax and birth control needs

Doctors aren’t sure whether it’s safe to take Fosamax during pregnancy. Talk with your doctor about your birth control needs with Fosamax if you’re sexually active and you or your partner can become pregnant. Your doctor can recommend if you should use birth control with this medication.

Fosamax: Taking while breastfeeding

It isn’t known if it’s safe to breastfeed while taking Fosamax.

If you have questions, talk with your doctor. They can recommend safe feeding options for your child.

Fosamax: Overdose

Serious effects can occur if you use more than the recommended dosage of Fosamax. Do not use more Fosamax than your doctor recommends.  

Symptoms of overdose

Symptoms that an overdose could cause include:

What to do in case of overdose

Call your doctor if you think you’ve taken too much of this drug. Also, you can call the American Association of Poison Control Centers at 800-222-1222 or use its online tool. However, if your symptoms are severe, call 911 or a local emergency number. Alternatively, go to the nearest emergency room right away.

Fosamax: Expiration, storage, and disposal

Here’s some information about Fosamax’s expiration date, as well as how to store and dispose of the drug.

Expiration. Your pharmacist will add an expiration date to the label on Fosamax’s packaging. This date is usually 1 year from the date the medication was dispensed to you. Expiration dates help ensure that a medication is effective during a period of time.

The Food and Drug Administration (FDA) advises that you avoid taking expired drugs. If you have an unused medication and it’s past the drug’s expiration date, talk with your pharmacist. They can let you know whether you might still be able to use the medication.

Storage. Many factors determine how long a medication remains good to use. These factors include how and where you store the drug. You should store Fosamax tablets at room temperature, between 59°F and 86°F (15°C and 30°C). Avoid storing it in areas where it could get damp or wet, such as bathrooms. The medication should be kept in a tightly sealed container.

Disposal. It’s important to safely dispose of Fosamax if you no longer need to take it and have unused medication. Doing so helps prevent others, including children and pets, from accidentally taking the drug. It also helps avoid causing harm to the environment.

Ask your pharmacist for information about disposing of Fosamax. Also, check out this page for several tips on safe medication disposal.

Fosamax: Questions for your doctor

If you have questions about Fosamax, talk with your doctor. They can help advise you on whether Fosamax could be a good treatment option for you.

Here’s a list of questions you may want to ask your doctor:

  • How does Fosamax compare to other treatments for my condition?
  • Is Fosamax safe to take based on my other medical conditions?
  • How long should I take Fosamax?
  • If I break a bone while taking Fosamax, what happens next?
  • Will I need to make any changes to my exercise habits if I start taking Fosamax?

Your doctor may also tell you about other treatment options for your condition. You may find this article helpful in learning about alternative drugs for osteoporosis.

Disclaimer: Healthgrades has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.

Medical Reviewer: Heather Bruce, PharmD
Last Review Date: 2022 Aug 15
THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.