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Fosamax Side Effects

Generic name: alendronate

Medically reviewed by Last updated on Feb 13, 2022.

Note: This document contains side effect information about alendronate. Some of the dosage forms listed on this page may not apply to the brand name Fosamax.


Common side effects of Fosamax include: decreased serum calcium and decreased serum phosphate. Other side effects include: arthralgia, myalgia, and ostealgia. See below for a comprehensive list of adverse effects.

For the Consumer

Applies to alendronate: oral solution, oral tablet, oral tablet effervescent

Side effects requiring immediate medical attention

Along with its needed effects, alendronate (the active ingredient contained in Fosamax) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking alendronate:

More common

  • Stomach pain

Less common

  • Difficulty with swallowing
  • heartburn
  • irritation or pain of the esophagus
  • muscle pain


Incidence not known

  • Blistering, peeling, or loosening of the skin
  • bloating or swelling of the face, arms, hands, lower legs, or feet
  • bone, joint, or muscle pain, severe and occasionally incapacitating
  • chest pain
  • chills
  • confusion
  • convulsions
  • cough
  • diarrhea
  • difficulty with breathing
  • difficulty with moving
  • heartburn
  • heavy jaw feeling
  • hives or welts
  • irregular heartbeats
  • itching
  • joint pain
  • large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • loosening of a tooth
  • muscle aching or cramping
  • muscle cramps in the hands, arms, feet, legs, or face
  • numbness and tingling around the mouth, fingertips, or feet
  • pain or burning in the throat
  • pain, swelling, or numbness in the mouth or jaw
  • rapid weight gain
  • red skin lesions, often with a purple center
  • red, irritated eyes
  • redness of the skin
  • sore throat
  • sores, ulcers, or white spots on the lips or tongue or inside the mouth
  • stomach cramps
  • swollen joints
  • tingling of the hands or feet
  • tremor
  • trouble breathing
  • unusual tiredness or weakness
  • unusual weight gain or loss
  • vomiting

Side effects not requiring immediate medical attention

Some side effects of alendronate may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

Incidence not known

  • Blurred vision or other change in vision
  • dizziness or lightheadedness
  • eye pain
  • feeling of constant movement of self or surroundings
  • general feeling of discomfort or illness
  • hair loss or thinning of the hair
  • sensation of spinning
  • sensitivity of the eye to light
  • tearing

For Healthcare Professionals

Applies to alendronate: oral solution, oral tablet, oral tablet effervescent


Generally, this drug has been well tolerated. Adverse effects usually have been mild when patients adhered to prescribing instructions.[Ref]


Very common (10% or more): Bone, muscle or joint pain (sometimes severe)

Common (1% to 10%): Muscle cramp, joint swelling

Rare (less than 0.1%): Osteonecrosis of the jaw, atypical subtrochanteric and diaphyseal femoral fractures

Postmarketing reports: Myalgia, low-energy femoral shaft and subtrochanteric fractures[Ref]


Common (1% to 10%): Alopecia, pruritus

Uncommon (0.1% to 1%): Rash, erythema

Rare (less than 0.1%): Rash with photosensitivity, severe skin reactions including Stevens-Johnson syndrome and toxic epidermal necrolysis[Ref]


Common (1% to 10%): Abdominal pain, dyspepsia, acid regurgitation, nausea, abdominal distension, constipation, diarrhea, flatulence, esophageal ulcer, gastritis, gastroesophageal reflux

Uncommon (0.1% to 1%): Gastric ulcer, esophagitis, esophageal erosions, melena, dysphagia, vomiting

Rare (less than 0.1%): Esophageal stricture, oropharyngeal ulceration, upper gastrointestinal PUB (perforation, ulcers, bleeding)

Postmarketing reports: Localized osteonecrosis of the jaw, generally associated with tooth extraction and/or local infection with delayed healing[Ref]

Nervous system

Common (1% to 10%): Headache, dizziness

Uncommon (0.1% to 1%): Dysgeusia[Ref]


Common (1% to 10%): Vertigo, asthenia, peripheral edema

Uncommon (0.1% to 1%): Transient symptoms of myalgia, malaise and rarely, typically in association with initiation of treatment[Ref]


Uncommon (0.1% to 1%): Eye inflammation (uveitis, scleritis, episcleritis)[Ref]


Rare (less than 0.1%): Symptomatic hypocalcemia (often in association with predisposing conditions)[Ref]


Rare (less than 0.1%): Urticaria, angioedema[Ref]


Postmarketing reports: Acute asthma exacerbations[Ref]

Frequently asked questions


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2. Bauer DC, Freedholm D, Thompson D, Musliner T, Black D, Ensrud K, Hochberg M, Nevitt M "Upper gastrointestinal tract safety profile of alendronate - The Fracture Intervention Trial." Arch Intern Med 160 (2000): 517-25

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11. Maconi G, Porro GB "Multiple ulcerative esophagitis caused by alendronate." Am J Gastroenterol 90 (1995): 1889-90

12. Nightingale SL "Important information regarding alendronate adverse reactions." JAMA 275 (1996): 1534

13. Abdelmalek MF, Douglas DD "Alendronate-induced ulcerative esophagitis." Am J Gastroenterol 91 (1996): 1282-3

14. Devogelaer JP "Oral alendronate induces progressive increases in bone mass of the spine, hip, and total body over 3 years in postmenopausal women with osteoporosis (vol 18, pg 141, 1996)." Bone 19 (1996): 78

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20. Levine J, Nelson D "Esophageal stricture associated with alendronate therapy." Am J Med 102 (1997): 489-91

21. Cameron RB "Esophagitis dissecans superficialis and alendronate: case report." Gastrointest Endosc 46 (1997): 562-3

22. Lourwood DL "The pharmacology and therapeutic utility of bisphosphonates." Pharmacotherapy 18 (1998): 779-89

23. Mortimer O, Yue QY "Alendronate - Risk for esophageal stricture." J Am Geriat Soc 46 (1998): 1581-2

24. Becker P, Watts NB "Alendronate increases spine and hip bone mineral density in women with postmenopausal osteoporosis who failed to respond to intermittent cyclical etidronate." Bone 24 (1999): 65-8

25. Black DM, Cummings SR, Thompson DE, et al. "Effect of alendronate on risk of fracture in women with low bone density but without vertebral fractures: results from the fracture intervention trial." JAMA 280 (1998): 2077-82

26. Clemmesen B, Daifortis A, McClung M, et al. "Alendronate prevents postmenopausal bone loss in women without osteoporosis: a double-blind, randomized, controlled trial." Ann Intern Med 128 (1998): 253-61

27. Wallace JL "Upper gastrointestinal ulceration with alendronate." Digest Dis Sci 44 (1999): 311-2

28. Peter CP "Upper gastrointestinal ulceration with alendronate - Response." Digest Dis Sci 44 (1999): 312-3

29. Beauchesne MF, Miller PF "Etidronate and alendronate in the treatment of postmenopausal osteoporosis." Ann Pharmacother 33 (1999): 587-99

30. Davidson M, Downs RW, Bone HG, Emkey R, Mulloy AL, McKeever C, Recker RR, We, Bell N, Greenspan SL, Miller SS, Meunier PJ "Alendronate and estrogen effects in postmenopausal women with low bone mineral density." J Clin Endocrinol Metab 85 (2000): 720-6

31. Graham DY, Malaty HM "Alendronate and naproxen are synergistic for development of gastric ulcers." Arch Intern Med 161 (2001): 107-10

32. Miller PD, Ettinger MP, Smith ME, Yates J, Licata AA, Melton ME, Mako B, Palmisano JJ, Wang LX, Woodson G "Rechallenge of patients who had discontinued alendronate therapy because of upper gastrointestinal symptoms." Clin Ther 22 (2000): 1433-42

33. Malaty, Graham "Alendronate and naproxen are synergistic for development of gastric ulcers (Vol 161, pg 107, 1921)." Arch Intern Med 161 (2001): 1862

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Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.