Alendronate (alendronic acid)

(Brand names: Fosamax®, Fosavance®, Binosto®)

Alendronate is a drug treatment for osteoporosis. It can help to strengthen bones, making them less likely to break. It is available as a weekly tablet, soluble tablet, or liquid that you drink.

Alendronate is a type of medication called a bisphosphonate. Bisphosphonates are the most common treatments for osteoporosis. Alendronate is usually the first treatment that people are offered to help improve their bone strength.

What does alendronate do and how does it work?

Alendronate can help to make your bones stronger and reduce your risk of broken bones.

Bones are made up of living tissue. The inside of our bones is constantly being broken down and rebuilt by specialist bone cells. As long as this process is in balance, your bones should stay healthy and strong.

But if the process becomes out of balance, our bodies can start to break down more bone than we build. This can cause the bones to become weaker and more likely to break easily.

Alendronate works by slowing down the cells that break down bone. This helps to restore the balance and make your bones stronger.

You may still break a bone while taking alendronate. If this happens, it doesn’t necessarily mean the drug isn’t working. No medication can stop all fractures, but taking alendronate will make them much less likely.

Alendronate is not a pain-relieving medicine, so it won’t reduce the pain caused by broken bones. But there are other treatments and ways to manage pain.

Who can have alendronate?

Alendronate may be suitable if you have osteoporosis, or if your risk of breaking a bone is high enough to need a drug treatment. It is licensed for use in women who have been through the menopause, and for men. Doctors will occasionally offer it to younger women.

Alendronate tablets are usually the first treatment that people are offered. There are other drug treatments available, but these generally won’t be an option unless alendronate is not suitable for you.

Alendronate can also be used after other treatments. For example, you might be offered alendronate if you’ve just finished a course of treatment and need to start taking a different drug straightaway.

When is alendronate not suitable?

Alendronate may not be suitable if you:

• have difficulty swallowing
• have a problem with your oesophagus (gullet or food pipe), such as Barrett’s oesophagus
• can’t stand or sit up for at least half an hour (see below)
• have severe kidney problems
• have a low blood calcium level (hypocalcaemia) – you’ll need to increase your intake of calcium and vitamin D before you can start alendronate
• are pregnant or breast-feeding.

How do I take alendronate?

Alendronate is available in the following forms:

• 1 tablet (70mg) every week – this is the most common way to take alendronate
• 1 soluble tablet (70mg) that you dissolve in water and drink every week
• 1 liquid medicine (containing 70mg of alendronate) that you drink every week
• 1 tablet (70mg alendronate with vitamin D) every week.

Make sure you take your alendronate on the same day each week. It may help to make a note in your diary or set a reminder on your phone.

The following steps are important for ensuring the treatment works properly. They will also help to make side effects less likely (see below).

Take alendronate as soon as you wake in the morning

It’s very important to take alendronate on an empty stomach. Then wait at least 30 minutes before having your first food or drink of the day (other than plain tap water). This is to make sure your body can absorb and use the drug.

If you forget to take your treatment, wait until the following morning before taking it. Then return to your usual day the following week.

Follow the instructions for your treatment

Tablets (generic alendronate, Fosamax®, Fosavance®):

Swallow your tablet whole, with a glass of plain tap water. It’s important not to crush, chew or suck it.

Soluble tablets (Binosto®):

Dissolve your weekly tablet in at least 120ml of water. Once the liquid has stopped fizzing, drink the medicine. Then drink at least 30ml (2 tablespoons) of plain tap water.

Liquid medicine (alendronate oral solution):

This comes in a small bottle containing a single weekly (100ml) dose. Swallow all of the medicine, then drink at least 30ml (2 tablespoons) of plain tap water.

Don’t take other medications or supplements during this time

If you take calcium supplements, wait at least half an hour after taking alendronate. This is because calcium can affect how well the drug is absorbed. Some doctors suggest waiting up to four hours, to leave even more time for the drug to be absorbed.

Stay upright for at least 30 minutes afterwards

You must not lie down for at least half an hour after taking alendronate, and until you've eaten something. This helps the treatment to go down quickly into the stomach where it is absorbed. Your food pipe is more likely to become irritated if you lie down straightaway.

How will my treatment be monitored?

When you start on alendronate, you may have an appointment after around three months, and again after one year. This is to check you’re taking your treatment properly and not having any problems. Tell the doctor, nurse or pharmacist if you have any side effects (see below). They may be able to suggest ways to help manage them.

If you break a bone while taking alendronate, speak to your GP. Breaking a bone doesn’t necessarily mean your treatment isn’t working. But it may be a good idea to have a bone health assessment.

After about five years on alendronate, you should have a formal treatment review. Ask your doctor when this should happen if you’re unsure. At this review, your doctor will check if you still need a drug treatment, and that alendronate is still the right treatment for you.

You may have a bone density scan as part of your review, which will give your doctor some information about your bone strength. But they will need to consider other things as well, such as whether you’ve broken any bones since starting on alendronate.

While there’s no way to prove for certain that your treatment is working, research has shown that drugs like alendronate do lower people's risk of broken bones.

After your review, your doctor may advise you to:

• stay on alendronate for another five years
• stop treatment for a year or two, if this is safe for you – this is known as a treatment pause
• start a different drug treatment instead of alendronate
• stop having any treatment.

Alendronate is a long-lasting treatment and should keep helping your bones for about 2-3 years after you stop having it. Your doctor can advise you on what’s best for you, based on your own situation.

What are the possible side effects?

As with any drug, alendronate can sometimes cause side effects. The most common side effects are listed below, along with some rare problems that might very occasionally happen after several years of treatment.

It is important to remember that in general, side effects are less common than many people think. Most people on alendronate don’t have any problems. Even if you do get side effects at first, they usually improve quickly and there are ways to manage them.

For a full list of possible side effects, look at the patient information leaflet that comes with your treatment. If you don’t have a copy, ask your doctor or pharmacist for one.

It’s important to understand that many of these problems aren’t actually caused by the drug. When a medicine is first tested, the people taking it have to report anything unusual to the researchers. The problems they report are often just as common in people who aren’t taking the drug.

The following table has information on the main side effects that were seen more often in people taking alendronate, rather than a dummy drug. For example, fewer than 1 person in every 10 people who take alendronate will get problems with their oesophagus (food pipe) or heartburn. The other 9 in every 10 people who take the drug will not have this problem.

Rare health risks:

If you do get any side effects that don’t go away, it may help to:

• make sure the problem isn’t caused by any other medication you are taking
• tell your doctor or pharmacist, who may be able to help find out what is causing the problem
• ask your doctor or pharmacist about other treatments that may suit you better.

Making a decision about treatment

As with any treatment, there are advantages and disadvantages to taking alendronate. You should think about these when deciding whether to have alendronate, and about what’s important to you. Here are some of the main things to consider.

Advantages

• It can help to reduce your risk of broken bones.
• It's available as a weekly tablet, soluble tablet, or liquid that you drink.
• It is effective for at least ten years of use.
• It keeps helping your bone strength for a while, even after you stop taking it.

Disadvantages

• As with all medications, some people get side effects.
• There are some possible health risks after several years of use, but these are rare.
• Tablets and liquid medicines won't be suitable for everyone.

If you've thought carefully about the advantages and disadvantages but still feel unsure, we have more information to help guide you through deciding whether or not to have a drug treatment.

Content reviewed: April 2023

How do I take alendronate? 

Hilary shares her alendronate (alendronic acid) routine and some of the things she wished she'd known when starting alendronate. She discusses how to make the most of her drug treatment, how to reduce side effects and what to do if she forgets to take her tablet. This film is part of our #BoneMatters series of events

Watch our webinar on osteoporosis drug treatments:

If you're thinking about taking a drug treatment for osteoporosis, you may be interested in watching a conversation between osteoporosis experts Dr Nicola Peel, Dr Zoe Paskins and Professor David Armstrong, who discussed drug treatments in May 2022 as part of our #BoneMatters series of events.

Read next:

• Getting the best from your treatment