Metformin - oral

Patient Medicine Information
Why do I need this medicine?
Metformin is used for diabetes. It helps treat your diabetes by keeping your blood sugar in control.

This medicine is meant to be taken as part of a complete diabetes care programme that should include exercise, a healthy diet and regular monitoring of blood sugar levels.
How do I take this medicine?
Take Metformin exactly as directed by your doctor or according to the instructions on the label. Do not take more or less than instructed by your doctor.

Metformin is available as a conventional tablet, extended-release tablet or oral solution.

If you are taking the conventional tablet, swallow it whole. Take it together with food or immediately after a meal.

If you are taking an extended-release type of tablet (usually labeled as “XL”, “ER”), swallow it whole. Do not divide, chew or crush the tablet. It is best to take it with the evening meal.

If you have been given the oral solution, use the pipette (dropper) supplied with each bottle to measure out your dose. Empty the contents of the dropper onto a spoon or directly into the mouth. Refer to the package insert for directions on how the dropper should be used. Take it together with food or immediately after a meal. Try to take it at the same time each day.

Metformin must be taken regularly for it to be effective. Continue taking this medicine even when you feel better. Do not stop taking it unless instructed by the doctor.
What should I do if I have forgotten to take this medicine?
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and return to your normal dosing schedule.

DO NOT double a dose under any circumstances.

If you often forget to take your medicine, let your doctor and pharmacist know.
When should I not use this medicine?
Alert your doctor if you have the following conditions:
  • heart disease or recent heart attack
  • metabolic acidosis (a condition in which the body produces too much acid)
  • liver disease
  • lung disease
  • severe kidney disease
  • excessive alcohol intake or alcohol addiction
as Metformin may not be suitable for you.

If you are going for a radiology procedure involving injection of a dye into the bloodstream, inform your doctor that you are taking this medicine.
What should I take note of while taking this medicine?
Inform your doctor if you have type 1 diabetes or in stress-related conditions such as fever, trauma, infection, surgery.

You are more likely to develop lactic acidosis (too much lactic acid accumulation in the body) while you are being treated with Metformin. You may be having lactic acidosis if you feel like vomiting or if you experience stomach pain, extreme tiredness, breathlessness or dizziness.

Let your doctor know if you are pregnant or breastfeeding.

If you are going for an operation, including minor surgery and dental work, inform your doctor or dentist that you are taking Metformin.

Be sure to check with your doctor or pharmacist before giving Metformin to a child or elderly person. Children and elderly people may be more sensitive to the side effects.

Keep your appointments with your doctor. Your doctor needs to monitor your condition and check your response to the medication regularly.
  • Your blood sugar level may be monitored by your doctor depending on your condition. He will advise you on how often you need to have it checked.
  • Your doctor may need to perform blood tests to make sure that your kidney function is normal before you take this medicine and thereafter depending on your doctor’s advice.
  • Other routine blood tests may also be done if you are taking this medicine for a long period of time.
If you are taking this medicine with other types of anti-diabetic medicines, you may have been warned about hypoglycaemia. Hypoglycaemia is the medical term for low blood sugar. It is important to recognise the symptoms of hypoglycaemia and correct the low blood sugar level. If you don't, you may faint.

How do I know if I am experiencing hypoglycaemia?

Some of the symptoms of hypoglycaemia include dizziness, headache, shaky hands, feeling hungry, weak or confused, problems speaking. These symptoms are your body's way of warning you that your blood sugar is dangerously low.

What should I do if I am experiencing hypoglycaemia?

You should take a drink or food containing sugar (e.g. fruit juice, soft drinks or sweets) at the first sign of hypoglycaemia. If your symptoms do not improve, get medical help. Keep some glucose tablets (also known as dextrose tablets) with you at all times.
What side effects could I experience?
Metformin may cause any of the following side effects: headache, nausea, vomiting, diarrhoea, constipation, stomach wind, heartburn or indigestion, abnormal stools, stomach pain, taste disorder, weakness, chills, nail disease, rash, redness and hot flushes, flu-like symptoms, coughs and common colds, and chest discomfort.

Some side effects may be serious, although they are not common. Alert your doctor quickly if you experience:
  • stomach discomfort, decreased appetite, tiredness, muscle pain, unusual sleepiness
  • pass out blood or black, tarry stools or vomit coffee-ground-like vomitus
  • fast and irregular heartbeat or difficulty breathing
Inform your doctor if any of these side effects do not go away or are severe, or if you experience other side effects.
Can I take this with other medicines?
Do not take Metformin if you must undergo a radiology procedure involving iodinated contrast agents (dyes).

Inform your doctor and pharmacist if you are taking any of these medicines:
  • medicines for diabetes e.g. insulin
  • medicines for heart disease or high blood pressure e.g. verapamil, ranolazine, captopril, losartan
  • medicines for water retention (“water pills”) e.g. hydrochlorothiazide
  • gastric medicines e.g. cimetidine
This list does not include all medicines that may interact with Metformin.

Always notify your doctor and pharmacist if you are taking any other medicines, including herbal tonics such as traditional Chinese medicines, supplements and medicines that you buy without a prescription.
What special dietary instructions should I follow?
Avoid alcohol. It is important to adhere to the diet prescribed by your doctor.
How should I store this medicine?
Store in a cool, dry place away from the reach of children. Protect from light.

Medicines must not be used past the expiry date.
This information is independently developed by MIMS based on metformin - oral and is provided for your reference only. It is not a replacement for and should only be used in conjunction with full consultation with a licensed healthcare professional, the information provided by your pharmacist and/or the manufacturer of the medication. It may not contain all the available information you require and cannot substitute professional medical care, nor does it take into account all individual circumstances. Although great effort has been made to ensure content accuracy, we shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2022 MIMS. All rights reserved. Powered by
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