Like all medicines, gliclazide can cause side effects, although not everyone gets them.
Side effects can be less likely if you take gliclazide tablets with a meal.
Common side effects
There are things you can do to help cope with these common side effects of gliclazide:
Stomach ache or indigestion
Try to rest and relax. It can help to eat and drink slowly, and have smaller and more frequent meals. Putting a heat pad or covered hot water bottle on your stomach may also help.
If you're in a lot of pain, speak to your pharmacist or doctor
Feeling sick (nausea)
Take your tablets with a meal. Stick to simple meals and avoid rich or spicy food.
Being sick (vomiting)
Take small, frequent sips of water or squash to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat vomiting without speaking to a pharmacist or doctor.
If you take the combined contraceptive pill or the progestogen-only pill and you're being sick, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Diarrhoea
Drink lots of fluids, such as water or squash, to avoid dehydration. Signs of dehydration include peeing less than usual or having dark, strong-smelling pee. Do not take any other medicines to treat diarrhoea without speaking to a pharmacist or doctor.
If you take the combined contraceptive pill or the progestogen-only pill and have severe diarrhoea for more than 24 hours, your contraception may not protect you from pregnancy. Check the pill packet for advice.
Constipation
Get more fibre into your diet, such as fresh fruit, vegetables and cereals, and drink plenty of water. Try to increase your level of exercise, for example by going for a daily walk or run.
Speak to a doctor or pharmacist if the advice on how to cope does not help and a side effect is still bothering you or does not go away.
Low blood sugar
Gliclazide can sometimes cause your blood sugar to go too low. The name for this is hypoglycaemia, or a "hypo".
Early warning signs of low blood sugar include:
- feeling hungry
- trembling or shaking
- sweating
- confusion
- difficulty concentrating
It's also possible for your blood sugar to go too low while you're asleep. If this happens, it can make you feel sweaty, tired and confused when you wake up.
Low blood sugar may happen if you:
- take too much gliclazide
- eat meals irregularly or skip meals
- are fasting
- do not eat a healthy diet and are not getting enough nutrients
- change what you eat
- exercise too much without eating enough carbohydrates
- drink alcohol, especially after skipping a meal
- have a hormone disorder, such as an underactive thyroid (hypothyroidism)
- have kidney or liver problems
Preventing a hypo
To prevent having a hypo, it's important to have regular meals, including breakfast. Never miss or delay a meal.
If you're planning to exercise more than usual, make sure you eat carbohydrates like bread, pasta or cereals before, during or afterwards.
Always carry a fast-acting carbohydrate with you. If you think you have low blood sugar, try having something to eat or drink that quickly gets sugar into your bloodstream. This could be something like sugar, fruit juice, jelly babies or glucose or dextrose tablets. Artificial sweeteners will not help.
This type of sugar will not last long in your blood, so you may also need to eat a starchy carbohydrate, like a sandwich or a biscuit.
Call your doctor or contact 111 if taking in sugar does not help or the hypo symptoms come back.
Make sure your friends and family know about your diabetes and the symptoms of low blood sugar levels so they can recognise a hypo if it happens.
Serious side effects
Serious side effects are rare.
Call a doctor or call 111 straight away if:
- the whites of your eyes turn yellow, or your skin turns yellow although this may be less obvious on black or brown skin – these can be signs of a liver problem
- you're paler than usual, you get prolonged bleeding, bruising, sore throat and high temperature – these can be signs of a blood disorder
Your eyesight may be affected for a short time, especially at the start of treatment, because of changes in your blood sugar levels. Do not drive, cycle or use tools or machinery until this gets better. If you are concerned and it does not go away, talk to your doctor.
Serious allergic reaction
It's possible to have a serious allergic reaction (anaphylaxis) to gliclazide.
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.
Other side effects
These are not all the side effects of gliclazide. For a full list, see the leaflet inside your medicine's packet.
You can report any suspected side effect using the Yellow Card safety scheme.