Gliclazide is a medicine used to treat type 2 diabetes.

Type 2 diabetes is an illness where the body doesn't make enough insulin, or the insulin that is made doesn't work properly. This causes high blood sugar levels.

Gliclazide lowers your blood sugar by increasing the amount of insulin your body produces.

It's available on prescription as tablets.

  1. Key facts

    • Gliclazide works by increasing the amount of insulin that your body makes. Insulin is the hormone that controls the level of sugar in your blood.
    • If you take gliclazide once a day, it's best to take it in the morning with breakfast.
    • Gliclazide can sometimes make your blood sugar level too low (hypoglycaemia). Carry some sweets or fruit juice with you to help when this happens.
    • Gliclazide may make you put on weight.
    • Gliclazide may also be called by the brand names Bilxona, Dacadis, Diamicron, Laaglyda, Nazdol, Vamju, Vitile, Ziclaseg, and Zicron.
  2. Who can take gliclazide

    Gliclazide is only for adults. Do not give this medicine to children under 18.

    Gliclazide isn't suitable for some people. Tell your doctor before starting the medicine if you:

    • have had an allergic reaction to gliclazide or to other similar medicines for diabetes
    • have insulin-dependent diabetes (type 1)
    • have ketone bodies and sugar in your urine
    • have severe kidney or liver disease
    • have a rare illness called porphyria
    • are taking miconazole (a treatment for fungal infections)
    • are breastfeeding
    • have an illness called G6PD-deficiency
    • need to have surgery
  3. How and when to take

    The dose of gliclazide can vary. Take this medicine as prescribed by your doctor.

    Swallow your gliclazide tablets whole with a glass of water, do not chew them.

    Different types of gliclazide tablets

    Gliclazide comes as 2 different types of tablets – normal (standard-release) and long-acting (slow-release).

    Standard-release tablets release gliclazide into your body quickly so you may need to take them several times a day depending on your dose.

    Slow-release tablets dissolve slowly which means you don't have to take them as regularly as the standard ones. One dose in the morning is usually enough.

    Your doctor or pharmacist will explain what type of gliclazide tablets you are on and how often to take them.

    How much will I take?

    For standard-release gliclazide, the maximum daily dose is 320mg (4 x 80mg tablets). If you need to take more than 160mg (2 x 80mg tablets) a day, take the tablets twice a day with your morning and evening meals.

    For slow-release gliclazide, the maximum daily dose is 120mg. Take your dose once a day before breakfast.

    Will my dose go up or down?

    Your doctor will check your blood sugar levels regularly and may adjust your dose of gliclazide if necessary.

    What if I forget to take it?

    If you miss a dose of gliclazide, take the next dose at the usual time. Do not take a double dose to make up for a forgotten dose.

    If you forget doses often, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways that are suitable for you and your medicines.

    What if I take too much?

    If you take too many gliclazide tablets, contact your doctor straight away. An overdose of gliclazide can cause low blood sugar.

    If you think you have low blood sugar, have some food or drink that quickly gets sugar into your bloodstream such as sugar cubes or fruit juice. 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.

  4. Side effects

    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

    Common side effects include:

    • stomach ache
    • feeling sick
    • vomiting
    • indigestion
    • diarrhoea
    • constipation

    Serious side effects

    Serious side effects are rare.

    Tell your doctor straight away if you get warning signs of a:

    • liver disorder – including yellowing of the skin or whites of the eye
    • blood disorder – including paleness, prolonged bleeding, bruising, sore throat and fever
    • skin disorder – including rash, redness, itching and hives. You can also have sudden swelling of eyelids, face, lips, mouth, tongue or throat that may make it hard to breathe.

    Your eyesight may be affected for a short time, especially at the start of treatment because of changes in your blood sugar levels.

    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
    • don't eat a healthy diet with enough nutrients in
    • change what you eat
    • increase your physical activity without eating more to compensate
    • drink alcohol, especially after skipping a meal
    • take some other medicines or natural remedies at the same time
    • have a hormone disorder such as hypothyroidism
    • have kidney or liver problems

    To prevent hypoglycaemia, 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 (bread, pasta, cereals) before, during or afterwards.

    Always carry a fast-acting carbohydrate with you, like sugar cubes, fruit juice, or some sweets in case your blood sugar level gets low. Artificial sweeteners won't help. You may also need to eat a starchy carbohydrate, like a sandwich or a biscuit, to maintain your blood sugar for longer.

    If taking in sugar does not help or if the hypo symptoms come back, contact your doctor or the nearest hospital.

    Make sure your friends and family know about your diabetes and the symptoms of low blood sugar level so they can recognize a hypo if it happens.

    These are not all the side effects of gliclazide. For a full list see the leaflet inside your medicine packet.

  5. How to cope with side effects

    What to do about:

    • feeling sick – take your tablets with a meal – stick to simple meals and avoid rich or spicy food
    • diarrhoea and vomiting – have small sips of water often if you have diarrhoea or you are being sick. It may also help to take oral rehydration solutions. You can buy these from a pharmacy or supermarket to prevent dehydration. Do not take any other medicines to treat diarrhoea or vomiting without speaking to a pharmacist or doctor
    • constipation – eat more high-fibre foods such as fresh fruit and vegetables and cereals, and drink plenty of water. Also exercise more regularly, for example, by going for a daily walk or run
    • weight gain – gliclazide can make you hungrier and retain water so it can be quite challenging to avoid putting on weight while you're taking it. Try to eat a healthy balanced diet without increasing your portion sizes so you don't gain too much weight. Regular exercise will also help to keep your weight stable

    You can report any suspected side effect to a UK safety scheme.

  6. Pregnancy and breastfeeding

    Gliclazide is not generally recommended in pregnancy and while breastfeeding.

    It's not clear whether gliclazide harms an unborn baby. For safety, your doctor will probably change your medicine to insulin before you become pregnant or as soon as you find out you're pregnant.

    If you take gliclazide while breastfeeding there's a risk of your baby getting low blood sugar. Talk to your doctor if you want to breastfeed.

    Tell your doctor if you plan to get pregnant, become pregnant or want to breastfeed.

  7. Cautions with other medicines

    There are some medicines that interfere with the way gliclazide works.

    Tell your doctor if you are taking any of these medicines:

    • steroid tablets such as prednisolone
    • some medicines used to treat heart problems and high blood pressure
    • medicines to treat bacterial or fungal infections such as clarithromycin or fluconazole
    • painkillers such as ibuprofen and aspirin (but not paracetamol)
    • medicines used to treat asthma such as salbutamol
    • male and female hormones such as testosterone, oestrogen and progesterone
    • other diabetes medicines

    Gliclazide may also increase the effects of medicines that thin your blood such as warfarin.

    Some women might need a small adjustment in their gliclazide dose after starting contraceptive pills as in rare cases they can increase blood sugar levels.

    Mixing gliclazide with herbal remedies and supplements

    Do not take the herbal remedy for depression, St John's wort. It may change the way your body processes gliclazide.

    Tell your doctor and pharmacist if you are taking any other medicines, including herbal remedies and supplements.

  8. Common questions