What the label lists and what reports show
Alendronate side effects
Alendronate's FDA label: “Most common adverse reactions (greater than or equal to 3%) are abdominal pain, acid regurgitation, constipation, diarrhea, dyspepsia, musculoskeletal pain, nausea.” FAERS holds 100,325 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is pain (13,848 reports).
- Generic listed
Check it at the source: the alendronate FDA label on DailyMed (effective March 12, 2026, Organon LLC); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of FOSAMAX?FOSAMAX may cause serious side effects. See " What is the most important information I should know about FOSAMAX? " The most common side effects of FOSAMAX are: Stomach area (abdominal) pain Heartburn Constipation Diarrhea Upset stomach Pain in your bones, joints, or muscles Nausea You may get allergic reactions, such as hives or swelling of your face, lips, tongue, or throat. Worsening of asthma has been reported. Tell your doctor if you have any side effect that bothers you or that does not go away. These are not all the possible side effects of FOSAMAX. For more information, ask your doctor or pharmacist. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. How do I store FOSAMAX? Store FOSAMAX at room temperature, 59°F to 86°F (15°C to 30°C). Keep FOSAMAX in a tightly closed container. […]
Source: FDA drug label, Organon LLC, effective March 12, 2026 (SPL set 14e931fd-2c5f-4d90-b7db-5980706f4a56), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (greater than or equal to 3%) are abdominal pain, acid regurgitation, constipation, diarrhea, dyspepsia, musculoskeletal pain, nausea.
Table 1: Osteoporosis Treatment Studies in Postmenopausal Women Adverse Reactions Considered Possibly, Probably, or Definitely Drug Related by the Investigators and Reported in Greater Than or Equal to 1% of Patients
| Reaction | FOSAMAX 10 mg/day for three years % (n=196) | Placebo % (n=397) | FOSAMAX 5 mg/day for 2 years and 10 mg/day for either 1 or 2 additional years % (n=3236) | Placebo % (n=3223) |
|---|---|---|---|---|
| abdominal pain | 6.6 | 4.8 | 1.5 | 1.5 |
| nausea | 3.6 | 4.0 | 1.1 | 1.5 |
| dyspepsia | 3.6 | 3.5 | 1.1 | 1.2 |
| constipation | 3.1 | 1.8 | 0.0 | 0.2 |
| diarrhea | 3.1 | 1.8 | 0.6 | 0.3 |
| flatulence | 2.6 | 0.5 | 0.2 | 0.3 |
| acid regurgitation | 2.0 | 4.3 | 1.1 | 0.9 |
| esophageal ulcer | 1.5 | 0.0 | 0.1 | 0.1 |
| vomiting | 1.0 | 1.5 | 0.2 | 0.3 |
| dysphagia | 1.0 | 0.0 | 0.1 | 0.1 |
| abdominal distention | 1.0 | 0.8 | 0.0 | 0.0 |
| gastritis | 0.5 | 1.3 | 0.6 | 0.7 |
| musculoskeletal (bone, muscle or joint) pain | 4.1 | 2.5 | 0.4 | 0.3 |
| muscle cramp | 0.0 | 1.0 | 0.2 | 0.1 |
| headache | 2.6 | 1.5 | 0.2 | 0.2 |
| dizziness | 0.0 | 1.0 | 0.0 | 0.1 |
| taste perversion | 0.5 | 1.0 | 0.1 | 0.0 |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following clinically significant adverse drug reactions are described elsewhere in the labeling: Upper Gastrointestinal Adverse Reactions [see Warnings and Precautions (5.1) ] Mineral Metabolism [see Warnings and Precautions (5.2) ] Musculoskeletal Pain [see Warnings and Precautions (5.3) ] Osteonecrosis of the Jaw [see Warnings and Precautions (5.4) ] Atypical Fractures Including Femoral Fractures [see Warnings and Precautions (5.5) ] Renal Impairment [see Warnings and Precautions (5.6) ] Glucocorticoid-Induced Osteoporosis [see Warnings and Precautions (5.7) ] Most common adverse reactions (greater than or equal to 3%) are abdominal pain, acid regurgitation, constipation, diarrhea, dyspepsia, musculoskeletal pain, nausea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Organon LLC, a subsidiary of Organon & Co., at 1-844-674-3200 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. …
Source: FDA drug label, Organon LLC, effective March 12, 2026 (SPL set 14e931fd-2c5f-4d90-b7db-5980706f4a56), via openFDA; the full label on DailyMed
What do FAERS reports show?
100,325 reports list alendronate among the medicines taken, each a report of something that happened, not proof the medicine caused it; 11,884 are coded as a death and 37,737 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 23 reactions below, 7 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Alendronate: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions