Alendronic acid is used to treat osteoporosis. Learn how to use the medication, its common side effects, special precautions to watch out for, and more.

What is this medication for?

• Alendronic acid belongs to a class of medication called “bisphosphonates”. They are used to treat and prevent osteoporosis – a condition which causes the bones to become weak and fragile. Bisphosphonates prevent bones from breaking down, hence, slowing down the process of osteoporosis. 
• Alendronic acid needs to be taken regularly for a long period of time to get its benefits. You should have  an adequate intake of Calcium and Vitamin D (from food or supplements) to strengthen your bones. Calcium is the major building block of bone, and Vitamin D helps in the absorption of Calcium by the body.

To reduce the risk of osteoporosis, you should engage in weight-bearing and muscle-strengthening exercises, stop smoking and consume alcohol in moderation

It may come as a plain oral tablet or an effervescent tablet. Check with your healthcare professional if you are unsure. 

How should I take or use this medication?

• Take Alendronic acid 1 tablet ONCE A WEEK on the same day every week.
  • Choose a day of the week that is most convenient to you e.g. every Monday or every Sunday
• Take this medication first thing in the morning upon waking up, on an empty stomach.
• For Oral tablet: Swallow the tablet whole with a full glass of plain water (no other drinks). Do not crush, chew or suck the tablet.
• For Effervescent tablet: Dissolve in at least 120mL of room temperature plain water. Drink the solution only after the fizzing has subsided and the tablet has completely dissolved, followed by at least 30mL of additional plain water. 
• Remain upright for at least 30 minutes after taking the medication. Do not lie down or bend over. You may sit, stand or do your usual activities such as walking or watching television. This is to prevent irritation of the oesophagus (“food pipe”)
• Do not stop taking your medication without checking with your healthcare professional.

What should I do if I forget to take or use this medication?

• If you missed by one day: Take 1 tablet the next day using the steps described above. Then, return to your usual dose the following week.
• If you missed by two or more days: Skip the missed dose for the week. Then, return to your usual dose the following week. 
• Take only one tablet at each time. Do not double your dose to make up for a missed dose.​

What precautions should I take when taking or using this medication?

Inform your healthcare professional if:

• You are allergic to this medication or any of the other ingredients in this medication
• You are pregnant, planning to become pregnant or breastfeeding
• You have any existing kidney problems

Maintain good oral hygiene and go for regular dental check-ups. Your doctor may also require you to visit a dentist before starting on Alendronic acid. Do Inform your dentist that you are taking Alendronic acid.

What are some common side effects of this medication?

• ​Generally, this medication has been well tolerated. Side effects are usually mild and may go away as the body adjusts to the medication. 
• Common side effects include:
  • Mild stomach disturbances (e.g. acid reflux, stomach fullness or bloatedness, diarrhoea or constipation)
  • Headache
  • Bone, muscle and/or joint aches

If you have any concerns regarding the side effects of Alendronic acid, discuss with your healthcare professional. Do not stop taking medication on your own.

What are some rare but serious side-effects that I need to seek medical advice immediately?

• Difficulty or pain with swallowing 
• Sore throat and/or heartburn that does not get better or becomes worse
• Prolonged gum pain and swelling 
• Any numbness/pain in the jaw, loosening of tooth, delayed healing of ulcer in the mouth. 
  • Always inform your dentist that you are taking this medication to avoid this rare but serious side effect.
• Any bone pain/persistent dull aching in hips, groin or thigh without any injury or trauma
• Symptoms of a drug allergy that include one or more of the following: 
  • swollen face/eyes/lips
  • difficulty in breathing
  • itchy skin rashes over your whole body

If any of these happens, stop taking your medication and see a doctor immediately as you will need treatment straight away.

What food or medication should I avoid when I take or use this medication?

• Do not eat/drink anything (other than plain water) or take any other medication for the next 30 minutes, because it would reduce absorption of this medication.
• Avoid any food or products that are high in calcium, iron or magnesium for at least 30 minutes (but preferably 2 hours) after taking the medication, for best absorption of this medication. 
  Examples of food/products to avoid are:
  • 3-in-1 coffee or tea, coffee or tea containing milk (i.e. Kopi, Kopi-C, Teh, Teh-C etc)
  • Dairy products e.g. milk, cheese or yogurt
  • Soya products e.g. soybean milk, soybean curd, tofu
  • Medications or supplements, e.g. antacids, calcium, iron or magnesium supplements, multivitamins.

However, this advice may vary, do follow the instructions given by your healthcare provider.

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children.

How do I throw away this medication safely?

Pack this medication into a black trash bag and seal it tightly before throwing into the rubbish chute or bin. 

Disclaimer

Please take note that the above is not a complete list of all possible side effects. If you have any concerns about your medication or if you have other side effects that you think are caused by this medication, please consult your doctor or pharmacist.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on Apr 2025