Alendronate

Pronunciation: a-LEN-droh-nate.

Generic name
alendronic acid (alendronate sodium)
Drug class
Oral bisphosphonate (aminobisphosphonate, bone resorption inhibitor)
Form
Tablet (5 mg, 10 mg, 35 mg, 40 mg, 70 mg) or oral solution
Route
Oral
Legal status
Prescription-only

Availability and supply rules vary by country

Trade names by country: United States · United Kingdom · Canada · Australia · New Zealand

Australia: Alendronate Sandoz; Fosamax Plus (5) · Full directory

What alendronic acid (alendronate sodium) is and how it works

Alendronate is a prescription-only oral bisphosphonate used to treat and help prevent osteoporosis and certain other bone conditions. It works by slowing the breakdown of bone, which helps maintain bone density and reduce fracture risk. (1)

Alendronate has a strict way it must be taken to avoid irritating your esophagus (food pipe) -- on an empty stomach, with plain water only, and staying upright afterward. Your prescriber will set your exact dose and how long you should take it.

Mechanism of action: how alendronic acid (alendronate sodium) works

Alendronate is a nitrogen-containing (amino)bisphosphonate that binds to bone mineral and inhibits osteoclast-mediated bone resorption, without directly interfering with bone mineralisation, leading to a net gain in bone mass over time. (1) (6)

What alendronic acid (alendronate sodium) is used for

Osteoporosis in postmenopausal women

Used to treat and to help prevent osteoporosis in postmenopausal women, reducing the risk of spine and hip fractures. (1) (2)

Osteoporosis in men

Used to increase bone mass in men with osteoporosis. (1)

Glucocorticoid-induced osteoporosis

Used to treat osteoporosis caused by long-term corticosteroid ('steroid') medicines. (1)

Paget's disease of bone

Used to treat Paget's disease of bone, a condition of abnormal bone remodelling. (1)

Before taking alendronic acid (alendronate sodium)

Do not take / not appropriate for

  • Do not take alendronate if you have abnormalities of the esophagus that delay its emptying, such as a stricture or achalasia. (all countries) (1) (2)
  • Do not take alendronate if you are unable to stand or sit fully upright for at least 30 minutes. (all countries) (1) (2)
  • Do not take alendronate if you have low blood calcium (hypocalcemia) -- this must be corrected by your prescriber before starting. (all countries) (1) (2)
  • Do not take alendronate if you have had a serious allergic reaction to it or any of its ingredients. (all countries) (1)

Tell your clinician about

  • Any swallowing problems or other esophagus (food pipe) or stomach conditions.
  • Any dental problems, planned dental surgery, or invasive dental procedures.
  • Any kidney problems, since alendronate is not recommended with significant kidney impairment.
  • Low blood calcium or vitamin D levels.
  • Pregnancy, plans for pregnancy, or breastfeeding.
  • All other medicines you take, especially calcium supplements, antacids, and aspirin or other NSAIDs.
(1) (2)

How to take alendronic acid (alendronate sodium)

  • Take first thing in the morning, at least 30 minutes before the first food, drink, or other medicine of the day.
  • Swallow the tablet whole with a full glass of plain water only (not mineral water, coffee, tea, or juice) -- do not crush or chew it.
  • Stay fully upright (sitting or standing) for at least 30 minutes after taking it, and until after you have eaten your first food of the day.
  • Never take it at bedtime or before getting up for the day.
  • If you miss a weekly dose, take it the next morning after you remember -- do not take two doses on the same day.
(1) (2)

Procedures and treatment changes

Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (1) (2) (3) (4) (5) (6)

Missed dose

For a once-weekly dose, if you forget it, take it the next morning after you remember, then go back to taking it on your usual chosen day -- do not take two tablets on the same day. For a daily dose, contact your prescriber or pharmacist for guidance specific to your regimen.

Overdose

Seek urgent medical attention if you think you have taken too much alendronate. Do not induce vomiting and do not lie down -- remain fully upright, since vomiting or lying down can increase the risk of esophageal irritation. A clinician may give milk or antacids to help bind the drug while you wait for emergency care. (6)

Side effects

Side effects and their urgency vary; report severe, persistent, or concerning symptoms.

Abdominal pain and acid regurgitation.

What to notice: Abdominal pain and acid regurgitation.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Constipation, diarrhea, and indigestion (dyspepsia).

What to notice: Constipation, diarrhea, and indigestion (dyspepsia).

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Musculoskeletal (bone, muscle, or joint) pain, which is sometimes severe.

What to notice: Musculoskeletal (bone, muscle, or joint) pain, which is sometimes severe.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1) (2)

Nausea.

What to notice: Nausea.

What to do: Discuss persistent or troublesome symptoms with the treating clinician or pharmacist. (1)

Serious warnings

Signs of esophageal (food pipe) irritation or injury — high caution

Symptoms: New or worsening difficulty or pain swallowing, pain behind the breastbone, or new/worsening heartburn.

Action: Contact your prescriber promptly and follow their guidance on whether to continue treatment -- these can signal esophagitis, ulcers, or erosion, which are sometimes severe enough to need hospital care. (1) (2)

Possible atypical thigh, hip, or groin fracture — high caution

Symptoms: New, dull, aching thigh or groin pain, especially after long-term use.

Action: Tell your prescriber promptly -- this can be an early warning sign of a rare atypical femoral fracture, and your prescriber will decide whether further assessment or a change in treatment is needed. (1) (2)

Possible osteonecrosis of the jaw — high caution

Symptoms: Jaw pain, swelling, numbness, a feeling of heaviness, or loosening of a tooth, particularly around the time of a dental extraction or other invasive dental procedure.

Action: Tell your prescriber and dentist promptly, and mention that you take alendronate before any invasive dental procedure -- maintaining good oral hygiene is also advised. (1) (2)

Signs of low blood calcium (hypocalcemia) — emergency

Symptoms: Muscle cramps or spasms, tingling in the fingers/toes or around the mouth, or seizures.

Action: Seek urgent medical attention -- hypocalcemia must be corrected before and monitored during alendronate treatment. (1) (2)

Interactions

  • Calcium supplements, antacids, and other medicines containing multivalent minerals reduce alendronate's absorption -- wait at least 30 minutes after your dose before taking them. (1) (2)
  • Food, coffee, tea, juice, and mineral water also reduce absorption if taken too soon after a dose -- plain water only, and wait the full 30 minutes. (2)
  • Aspirin-containing products and other NSAIDs can increase the risk of upper gastrointestinal irritation when combined with alendronate. (1) (2)

Pregnancy, breastfeeding, kidney/liver function, age

Pregnancy

Alendronate is not recommended in pregnancy. Bisphosphonates are taken up into bone and released slowly over years, which is a theoretical concern for the developing fetus even after treatment has ended. If pregnancy occurs or is planned, discuss this with your prescriber promptly. (1) (2) (3) (4) (5) (6)

Breastfeeding

It is not known whether alendronate passes into human breast milk. Discuss the benefits and risks of breastfeeding with your prescriber. (1) (2) (3) (4) (5) (6)

Children

Not established as safe and effective for use in children. (1) (2) (3) (4) (5) (6)

Elderly

Widely used in older adults, who make up much of the population treated for osteoporosis; kidney function should be checked given age-related decline. (1) (2) (3) (4) (5) (6)

Hepatic_impairment

No specific dose adjustment is described in the sources reviewed for liver impairment. (1) (2) (3) (4) (5) (6)

Renal_impairment

Not recommended for patients with significant kidney impairment (creatinine clearance below 35 mL/min). (1) (2) (3) (4) (5) (6)

Monitoring

Before starting

  • Correction of hypocalcemia and vitamin D deficiency
  • Baseline bone mineral density
  • Dental review if invasive dental work is anticipated
  • Kidney function

During treatment

  • Periodic bone mineral density assessment.
  • Serum calcium and phosphate, particularly in Paget's disease or with concurrent corticosteroid use.
  • Ongoing dental hygiene and prompt reporting of jaw symptoms.
  • Reporting of new thigh, hip, or groin pain.
(1)

Storage

Store at room temperature, in the original container, protected from moisture. Keep out of reach of children.

Professional information

Clinician-facing context only, sourced from the current US FDA prescribing information and UK SmPC; verify against the current full label before prescribing.

United States

Indication: Postmenopausal osteoporosis, male osteoporosis, glucocorticoid-induced osteoporosis, Paget's disease

Dose summary: Treatment: 10 mg daily or 70 mg once weekly. Prevention (postmenopausal women): 5 mg daily or 35 mg once weekly. Glucocorticoid-induced osteoporosis: 5 mg daily (10 mg daily for postmenopausal women not on estrogen). Paget's disease: 40 mg daily for six months. Optimal treatment duration not established; consider re-evaluation after 3-5 years in low-fracture-risk patients.

Renal context: Not recommended with creatinine clearance below 35 mL/min. (1)

United Kingdom

Indication: Postmenopausal osteoporosis

Dose summary: 70 mg once weekly, administration instructions as above.

Renal context: Not established in the source reviewed beyond the US renal cut-off; caution advised. (2)

Mechanism of action

Hepatic guidance

No specific hepatic dose adjustment described in the sources reviewed.

Overdose note

Overdose may cause hypocalcemia, hypophosphatemia, and upper gastrointestinal adverse events (esophagitis, gastritis, ulcer, mucosal erosion). Milk or antacids may be given to bind alendronate; the patient should remain fully upright and not be given anything to induce vomiting because of esophageal irritation risk. (1) (6)

Frequently asked questions

Is alendronate available in the US, UK, Europe, Canada, Australia, and New Zealand?

Yes, alendronate (originator brand Fosamax, plus many generics) is approved and available in all of these regions. (1) (3) (2) (4) (5) (6)

Why do I have to stay upright after taking alendronate?

Alendronate can irritate the esophagus (food pipe). Staying upright for at least 30 minutes, and never taking it at bedtime or before getting up, helps the tablet pass through quickly and reduces the risk of irritation or injury. (1) (6)

Can I take alendronate with my calcium supplement?

Not at the same time. Calcium, antacids, and other minerals block alendronate's absorption, so you should wait at least 30 minutes after your alendronate dose before taking them, or take them at a different time of day as your prescriber advises. (1) (2)

What is the mechanism of action of alendronic acid (alendronate sodium)?

Alendronate is a nitrogen-containing (amino)bisphosphonate that binds to bone mineral and inhibits osteoclast-mediated bone resorption, without directly interfering with bone mineralisation, leading to a net gain in bone mass over time. (1) (6)

What is the generic name of Alendronate?

The generic name is alendronic acid (alendronate sodium). (1)

What class of drug is alendronic acid (alendronate sodium)?

Alendronate is classed as: Oral bisphosphonate (aminobisphosphonate, bone resorption inhibitor). (1)

References

  1. FOSAMAX (alendronate sodium) tablets and oral solution -- full prescribing informationU.S. Food and Drug Administration / DailyMed (NIH), full prescribing information, Organon (Merck legacy product) · United States · accessed 2026-07-29 · source 1
  2. Fosamax Once Weekly 70 mg Tablets -- Summary of Product Characteristicselectronic medicines compendium (emc), United Kingdom · United Kingdom · accessed 2026-07-29 · source 2
  3. Adrovance (alendronic acid / colecalciferol) -- European Public Assessment Report; plain alendronic acid authorised across the EU via national/mutual-recognition procedures as the long-established generic bisphosphonateEuropean Medicines Agency (EMA) · European Union · accessed 2026-07-29 · source 3
  4. FOSAMAX (alendronate sodium) Product Monograph, Bone Metabolism RegulatorHealth Canada product monograph · Canada · accessed 2026-07-29 · source 4
  5. ALENDRONATE SANDOZ (alendronic acid 70 mg tablets) -- ARTG registration; Fosamax Plus formulations also ARTG-registeredTherapeutic Goods Administration (TGA), Australia · Australia · accessed 2026-07-29 · source 5
  6. Fosamax (alendronate sodium 70 mg tablets) New Zealand Data SheetMedsafe (New Zealand regulator) · New Zealand · accessed 2026-07-29 · source 6

Brand names by country

Single-ingredient alendronic acid (alendronate sodium) names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.

Priority countries

United States

  • Fosamax (1)FDA approved currently labeled · 5 mg, 10 mg, 35 mg, 40 mg, 70 mg · Organon (legacy Merck product)

United Kingdom

  • Fosamax Once Weekly (2)MHRA licensed emc smpc confirmed · 70 mg · Organon Pharma (UK) Limited

Canada

  • ALENDRONATE
  • ACH-ALENDRONATE
  • FOSAMAX
  • TEVA-ALENDRONATE
  • APO-ALENDRONATE
  • RAN-ALENDRONATE
  • VAN-ALENDRONATE
  • ACT ALENDRONATE
  • MYLAN-ALENDRONATE
  • SANDOZ ALENDRONATE

Australia

  • Alendronate Sandoz; Fosamax Plus (5)TGA ARTG registered confirmed · 70 mg · Sandoz Pty Ltd (generic); Organon Pharma Pty Ltd (Fosamax Plus)

New Zealand

  • Fosamax (6)Medsafe approved confirmed · 70 mg · Organon New Zealand
View brands in additional countries.

European Union

Fosavance / Adrovance (alendronic acid + colecalciferol, centrally authorised); plain alendronic acid generics nationally authorised across member states (3)

This page provides general reference information about alendronate and is not a substitute for advice from the prescriber managing your treatment. All dosing and treatment decisions should be made with your prescriber.

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