Alendronic acid

  • Alendronic acid is used to help prevent or treat osteoporosis.
  • It is very important that you carefully follow the instructions you have been given for taking alendronic acid.
  • If you experience any pain, heartburn, or difficulty swallowing, let your doctor know straight away.
  • Good dental hygiene is particularly important while you are taking alendronic acid - this means that you must brush your teeth regularly and have regular dental check-ups.
Type of medicine Bisphosphonate
Used for Treatment of osteoporosis in men and postmenopausal women
Prevention of osteoporosis in postmenopausal women
Also called Sodium alendronate
Fosamax® Once Weekly
Fosavance® (alendronic acid with colecalciferol/vitamin D3)
Available as Tablets and oral liquid

Osteoporosis is a bone disease which causes bones to become brittle and fragile, making them prone to breaks and fractures. Old bone is constantly being broken down and replaced by new bone. After the age of about 30-35 years, bone begins to lose density because the old bone is being lost faster than new bone can replace it.

Alendronic acid helps to treat and prevent osteoporosis by preventing the loss of bone and by helping to rebuild lost bone. By doing this, it reduces the risk of spinal and hip fractures.

Alendronic acid can be combined with colecalciferol (also known as vitamin D3) which helps the bones absorb calcium. The body's main source of colecalciferol is from exposure to sunlight although it is also present in small amounts in some foods such as oily fish. As we get older, the colecalciferol we absorb from sunlight sometimes needs supplementing.

Before taking alendronic acid make sure your doctor or pharmacist knows:

  • If you are pregnant, trying for a baby or breast-feeding.
  • If you have kidney problems.
  • If you have difficulty or pain on swallowing, or any other swallowing problems.
  • If you have had a stomach ulcer, stomach bleeding or any surgery on your upper digestive system within the previous year.
  • If you have any other problems with your stomach, throat or upper digestive system.
  • If you are unable to stand or sit upright for 30 minutes.
  • If you know you have a low blood calcium level.
  • If you are taking other medicines, including those available to buy without a prescription, herbal and complementary medicines.
  • If you have ever had an allergic reaction to this or to any other medicine.
  • Before starting this treatment, read the manufacturer's printed information leaflet from inside the pack.
  • It is important that you take alendronic acid exactly as your doctor has told you, as serious irritation of your throat can occur otherwise.
  • Swallow alendronic acid tablets whole - do not crush or chew them.
  • Take the tablets with a full glass of water (200 ml or 7 fl. oz.).
  • Take alendronic acid at least 30 minutes before eating breakfast or having anything to drink other than plain water.
  • Stand or sit upright for at least 30 minutes after swallowing your dose and do not lie down until after you have eaten breakfast.
  • If you are taking other medicines, wait at least 30 minutes after taking alendronic acid before taking them. If you are unsure or have any questions about your other medicines, ask your doctor or pharmacist for advice.
  • Never take alendronic acid before getting up in the morning or at bedtime.
  • If you have been told to take one dose a week, you must take your doses on the same day of each week.
  • If you are taking daily doses of alendronic acid and forget to take a dose, don't worry, just skip the forgotten dose and take the next dose when it is due. Do not take two doses together to make up for a forgotten dose.
  • If you are taking weekly doses of alendronic acid and forget to take a dose, take a dose on the following morning and then continue as normal on the day when your next dose is due.
  • Keep your regular appointments with your doctor so your progress can be monitored.
  • If you buy any medicines, check with a pharmacist that they are safe to take with alendronic acid.
  • If you are having any dental treatment, tell your dentist that you are taking alendronic acid as some dental treatments may not be recommended.
  • Smoking can increase the loss of bone in osteoporosis. If you are a smoker, ask your doctor or pharmacist for advice on stopping.
  • Eating a well-balanced diet and taking regular exercise can help bones stay strong. Remember to follow any lifestyle advice your doctor has given you.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Common side-effects - these affect less than 1 in 10 people who take this medicine What can I do if I experience this?
Heartburn, indigestion, abdominal pain, bloating Make sure you carefully follow the directions for taking alendronic acid and remain standing or sitting for at least half an hour afterwards. If the symptoms get worse, let your doctor know straight away
Diarrhoea Drink plenty of water to replace any lost fluids
Constipation Try to eat a well-balanced diet containing plenty of fibre and drink 6-8 glasses of water a day
Headache Ask your pharmacist to recommend a suitable painkiller. If the headache continues, speak with your doctor
Black or bloody stools Tell your doctor about this straight away
Muscle or joint pain If troublesome, speak with your doctor


  • If you experience any pain or difficulty swallowing, any new or worsening heartburn, or chest pain, you should stop taking alendronic acid and speak with your doctor straight away.
  • If you experience any pain or numbness in your jaw, or any problems with your mouth or teeth, tell your doctor as soon as possible.
  • If you experience any thigh, hip, or groin pain, tell your doctor as soon as possible.

If you experience any other symptoms which you think may be due to this medicine, speak with your doctor or pharmacist.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.
  • If you are having an operation or any dental treatment, tell the person carrying out the treatment which medicines you are taking.
  • Never take more than the prescribed dose. If you suspect that you have taken, or someone else has taken, an overdose of this medicine, go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.
  • This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
  • Never keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
  • If you have any questions about this medicine ask your pharmacist.

Further reading & references

  • British National Formulary; 62nd Edition (Sep 2011) British Medical Association and Royal Pharmaceutical Society of Great Britain, London
  • Manufacturer's PIL, Fosamax®; Manufacturer's PIL, Fosamax®, Merck Sharp & Dohme, electronic Medicines Compendium. Dated March 2011.
  • Manufacturer's PIL, Fosamax® Once Weekly; Manufacturer's PIL, Fosamax® Once Weekly, Merck Sharp & Dohme, electronic Medicines Compendium. Dated May 2011.
  • Manufacturer's PIL, Fosavance®; Manufacturer's PIL, Fosavance®, Merck Sharp & Dohme, electronic medicines Compendium. Dated March 2011.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Last Checked:
Document ID:
3626 (v25)
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