Like all medicines, alendronic acid can cause side effects in some people, but many people have no side effects, or only minor ones.
Side effects of alendronic acid
These common side effects of alendronic acid happen in more than 1 in 100 people. There are things you can do to help cope with them:
Indigestion, bloating or wind
Try to stay upright for at least 30 minutes after taking alendronic acid. It might also help to eat smaller meals more often. You could also try eating and drinking more slowly, and increase your level of exercise if you can.
Make sure you follow the instructions for taking alendronic acid carefully.
If the symptoms do not go away or get worse, contact your doctor straight away.
Constipation
Eat more high-fibre foods such as fresh fruit, vegetables and cereals. Try to drink several glasses of water or squash every day. If you can, try to increase your level of exercise. If this does not help, talk to your pharmacist or doctor.
Diarrhoea
Drink plenty of water to avoid dehydration. Speak to a pharmacist if you have signs of dehydration, such as peeing less than usual or having dark, strong-smelling pee.
Do not take any medicines to treat diarrhoea without speaking to a pharmacist or doctor.
If you take the combined contraceptive pill or the progestogen-only pill and you have severe, watery diarrhoea or any diarrhoea that lasts for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Feeling dizzy or a spinning sensation (vertigo)
Stop what you're doing, and sit or lie down until you feel better. If you've just taken alendronic acid try to avoid lying down for 30 minutes.
Do not drive, cycle or use tools or machinery until your dizziness has gone.
It's best not to drink alcohol until you see how the medicine affects you.
Headaches, muscle or joint pain
Make sure you rest and drink plenty of fluids. Try not to drink too much alcohol.
Ask your pharmacist to recommend a painkiller, and talk to your doctor if the pain does not go away or is severe.
Swollen joints, hands or legs
Try to rest. Avoid standing for long periods of time if you have swollen legs, and put your feet on a stool or cushion to raise your legs when you're sitting.
Talk to your doctor if the swelling is severe or does not go away.
Feeling sleepy or tired
Do not drive, cycle or use tools or machinery if you're feeling tired. Try not to drink any alcohol, as this will make you feel more tired.
Hair loss
Thinning hair or mild hair loss in itself can be stressful but it's not usually a sign of anything to worry about. Talk to your pharmacist or doctor if you're concerned.
Speak to a doctor or pharmacist if the advice on how to cope does not help and these side effects bother you or do not go away.
Serious side effects
Some people may have serious side effects when taking alendronic acid.
Stop taking alendronic acid and speak to a doctor or call 111 straight away if you have heartburn (or heartburn that gets worse), or problems or pain when swallowing. These may be signs of ulcers in your food pipe (oesophagus).
Other serious side effects are rare, but call a doctor or call 111 straight away if you have:
- flu-like symptoms, such as aching muscles, generally feeling unwell and sometimes with a high temperature – this is more likely to happen when you first start taking alendronic acid
- a loose tooth, mouth sores, or swelling or pain in your mouth or jaw – contact your dentist as well as your doctor, as this could be a sign of damage to your jawbone
- pain, weakness or discomfort in your thigh, hip or groin – this happens rarely but may be an early sign of a possible broken thigh bone
- severe pain in your joints, muscles or bones
- black or red poo – these can be signs of an ulcer or bleeding from your gut
- blurred vision, painful or red eyes – these can be signs of swelling of the eye
- muscle cramps or spasms, a tingling sensation in your fingers or around your mouth – these can be symptoms of low calcium levels in your blood
Serious allergic reaction
In rare cases it's possible to have a serious allergic reaction (anaphylaxis) to alendronic acid.
Immediate action required: Call 999 now if:
- your lips, mouth, throat or tongue suddenly become swollen
- you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
Do not drive yourself to A&E.
The person you speak to at 999 will give you advice about what to do.
Other side effects
These are not all the side effects of alendronic acid. For a full list, see the leaflet inside your medicine packet.
Reporting side effects
You can report any suspected side effect using the Yellow Card safety scheme.
Visit the Yellow Card website for more information about reporting side effects.