Side Effects of Alendronate for Osteoporosis
Alendronate is generally well-tolerated when taken correctly, but you should be aware of common gastrointestinal symptoms and rare but serious complications that require specific precautions.
Common Side Effects (Occur in 1-7% of patients)
Gastrointestinal Effects
- Abdominal pain occurs in approximately 3.7-6.6% of patients, along with nausea (1.9-3.6%), dyspepsia/indigestion (2.7-3.6%), and acid reflux (1.9-2.0%) 1
- Constipation (0.8-3.1%), diarrhea (3.1%), and flatulence (0.4-2.6%) are also reported 1
- These symptoms are usually mild, transient, and similar in frequency to placebo when the medication is taken properly 1
Musculoskeletal Effects
- Bone, muscle, or joint pain occurs in 2.9-4.1% of patients 1
- Muscle cramps may occur in up to 1% of patients 1
- Some patients develop severe bone, joint, or muscle pain that requires discontinuation 1
Other Common Effects
- Headache (2.6%), dizziness (1.0%), and mild decreases in blood calcium and phosphate levels (asymptomatic in most cases) 1
Serious Side Effects (Rare but Important)
Esophageal Problems (Most Critical to Prevent)
- Esophageal irritation, inflammation, or ulcers can occur if the medication is not taken correctly 1
- You must take alendronate with a full glass of water (6-8 ounces), remain completely upright (sitting or standing) for at least 30 minutes, and take nothing else by mouth during this period 1
- Stop the medication immediately and contact your provider if you develop chest pain, new or worsening heartburn, or difficulty/pain with swallowing 1
Low Blood Calcium (Hypocalcemia)
- Alendronate can lower calcium levels in your blood, especially if you already have low calcium before starting treatment 1
- Symptoms include muscle spasms, twitches, cramps, numbness or tingling in fingers, toes, or around the mouth 1
- Your provider should ensure adequate calcium (1000-1200 mg/day) and vitamin D (800 IU/day) supplementation throughout treatment 2, 3
Long-Term Risks (Increase After 5 Years of Treatment)
Osteonecrosis of the Jaw (ONJ)
- Very rare at less than 1 case per 100,000 person-years with standard osteoporosis dosing 4, 2
- Risk increases with longer treatment duration and is most strongly associated with recent dental surgery or tooth extraction 2
- Complete any necessary dental work before starting alendronate 2
- Practice good oral hygiene during treatment 1
Atypical Femoral Fractures
- Unusual low-energy fractures in the thigh bone occur at rates of 3.0-9.8 cases per 100,000 patient-years 4, 2
- Risk increases significantly after 5 years: from 1.78 per 100,000 with less than 2 years of treatment to over 100 per 100,000 with 8+ years 4
- New or unusual pain in your hip, groin, or thigh requires immediate medical evaluation 1
Cardiovascular Concerns
- Early concerns about atrial fibrillation have not been confirmed by most recent evidence, with no clear association established 4
- Some studies reported increased cardiovascular events, but a recent meta-analysis found no significant association 4
Treatment Duration and Safety
- The American College of Physicians recommends 5 years as the standard treatment duration 4, 2
- After 5 years, your provider should reassess your fracture risk to determine if continuing treatment is necessary 4, 2
- Extending treatment beyond 5 years reduces vertebral fractures but increases the risk of rare serious complications 2
What You Should Do
- Take the medication exactly as prescribed: first thing in the morning, with a full glass of plain water, remain upright for 30 minutes, and wait before eating or drinking anything else 1
- Ensure adequate calcium and vitamin D intake as recommended by your provider 2, 3
- Complete dental work before starting treatment 2
- Report any new symptoms immediately, especially chest pain, difficulty swallowing, unusual thigh/hip/groin pain, or signs of low calcium 1
- Discuss with your provider after 5 years of treatment whether continuing is appropriate for your individual fracture risk 4, 2