Metformin Side Effects

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Answer the side-effect intent for metformin without diagnosing; distinguish common from serious reactions and give safe next-step/reporting guidance.

Part of diabetes & weight management side effects.

What is metformin?

Metformin contains the active ingredient Metformin hydrochloride.

• Active ingredient — Metformin hydrochloride
• Registration number — 40/21.2/0466; 40/21.2/0467; A40/21.2/0466
• Registration holder — Shanur Healthcare (Pty) Ltd

It is approved for:

• METFORMIN ASCENDIS contains metformin, a medicine to treat diabetes
• It belongs to a group of medicines called biguanides
• METFORMIN ASCENDIS indicated in treating non-insulin dependent diabetes particularly in overweight patients, when dietary management and exercise alone does not control blood glucose level
• In children over 12 years of age and adolescents with type 2 diabetes, METFORMIN ASCENDIS may be used as alone or in combination with insulin

Common side effects of metformin

Not everyone gets side effects. The effects below are those listed in the South African approved leaflet, grouped using the leaflet’s own frequency wording.

Frequent side effects

• Digestive problems, such as feeling sick (nausea), being sick (vomiting), diarrhoea, bellyache (abdominal pain) and loss of appetite
• Change in taste
• Decrease or low vitamin B12 levels in the blood (symptoms may include extreme tiredness (fatigue), a sore and red tongue (glossitis), pins and needles (paraesthesia) or pale or yellow skin)

Less frequent side effects

• Abnormalities in liver function tests or hepatitis (inflammation of the liver which may cause tiredness, loss of appetite, weight loss, with or without yellowing of the skin or whites of the eyes)
• Skin reactions as redness of skin (erythema), itching or an itchy rash (hives). Side effects with frequency unknown:
• Lactic acidosis (vomiting, stomach ache, muscle cramps, a general feeling of not being well with severe tiredness, difficulty in breathing, reduced body temperature and heartbeat)

Serious side effects and warning signs

This leaflet does not set out a separate list of serious side effects. The general warning signs below apply to any medicine.

General warning signs that apply to any medicine

How long can side effects last?

How long a side effect lasts depends on the effect, the product, how long it has been used, and the person. Some effects ease within days as the body adjusts. Others continue for as long as the product is used. A few can persist after stopping, and some need review rather than waiting.

• Settling effects — mild effects that ease over the first days or weeks of use
• Ongoing effects — effects that continue while the product is being used and improve after stopping
• Persistent effects — effects that continue after stopping and need medical review
• Delayed effects — effects that appear after weeks or months rather than immediately

Which of these applies to a particular effect is a clinical question. If a side effect is not settling, is getting worse, or is affecting your daily life, that is worth a conversation with a pharmacist or doctor regardless of how long it has been going on.

Factors that may affect side effects

The approved leaflet identifies the following cautions and factors.

Do not use it at all if

• if you are hypersensitive (allergic) to metformin hydrochloride or any of the other ingredients of METFORMIN ASCENDIS (listed in section 6)
• If you have kidney problems such as kidney failure of kidney disease or condition which may alter kidney function such as:
• dehydration (significant loss of water from the body)
• severe infection
• shock
• if you have liver disease
• if you suffer from heart attack or heart failure, severe breathing problems, a past history of lactic acidosis, diabetic coma, ketoacidosis
• if you drink a lot of alcohol Make sure you ask your doctor for advice, if:
• you need to have an examination such as X-ray or scan involving the injection of contrast medicines that contain iodine into your bloodstream
• you need to have major surgery You must stop taking METFORMIN ASCENDIS for a certain period of time before and after the examination or the surgery. Your doctor will decide whether you need any other treatment for this time. It is important that you follow your doctor’s instructions precisely

Use with care, and tell your doctor, if

• Risk of lactic acidosis METFORMIN ASCENDIS may cause a very rare, but very serious side effect called lactic acidosis, particularly if your kidney are not working properly. The risk of developing lactic acidosis is also increased with uncontrolled diabetes, serious infections, prolonged fasting or alcohol intake, dehydration, liver problems and any medical conditions in which a part of the body has a reduced supply of oxygen (such as acute severe heart disease). If any of the above apply to you, talk to your doctor for further instructions
• Stop taking METFORMIN ASCENDIS for a short time if you have a condition that may be associated with dehydration (significant loss of body fluids) such as severe vomiting, diarrhoea, fever, exposure to heat or if you drink less fluid than normal. Talk to your doctor for further instructions. Stop taking METFORMIN ASCENDIS and contact a doctor or the nearest hospital immediately if you experience some of the symptoms of lactic acidosis, as this condition may lead to coma. Symptoms of lactic acidosis include:
• vomiting
• stomach ache (abdominal pain)
• muscle cramps
• a general feeling of not being well with severe tiredness
• difficulty in breathing
• reduced body temperature and heartbeat. Lactic acidosis is a medical emergency and must be treated in a hospital. If you need to have major surgery you must stop taking METFORMIN ASCENDIS during and for some time after the procedure. Your doctor will decide when you must stop and when to restart your treatment with METFORMIN ASCENDIS. METFORMIN ASCENDIS on its own does not cause hypoglycaemia (a blood glucose level which is too low). However, if you take METFORMIN ASCENDIS together with other medicine to treat diabetes that can cause hypoglycaemia (such as sulphonylureas, insulin, meglitinide), there is a risk of hypoglycaemia. If you experience symptoms of hypoglycaemia such as weakness, dizziness, increased sweating, fast heart beating, visions disorders or difficulty in concentration, it usually helps to eat or drink something containing sugar. During treatment with METFORMIN ASCENDIS, your doctor will check your kidney function at least once a year or more frequently if you are elderly and/or if you have worsening kidney function. Tell your doctor if you suffer from a blood disease that is caused by a deficiency of vitamin B12. Children and adolescents The diagnosis of type 2 diabetes mellitus should be confirmed before treatment with metformin is started. A careful follow-up of the effect of metformin on these parameters in metformin-treated children, especially prepubescent children is recommended

Pregnancy and breastfeeding

• If you are pregnant or breastfeeding, think you may be pregnant or are planning to have a baby, please consult your doctor, pharmacist or other health care provider for advice before taking METFORMIN ASCENDIS
• Speak to your doctor in case any changes will be needed to your treatment or monitoring of your blood glucose levels
• This medicine is not recommended if you are breast-feeding or if you are planning to breast-feed your baby

Interactions and medicines to check

The approved leaflet names these interactions.

• medicines which increase urine production (diuretics)
• medicines used to treat pain and inflammation (NSAID and COX-2 inhibitors, such as ibuprofen and celecoxib)
• certain medicines for the treatment of high blood pressure (ACE inhibitors and angiotensin II receptor antagonists)
• beta-2 agonist such as salbutamol or terbutaline (used to treat asthma)
• corticosteroids (used to treat a variety of conditions, such as severe inflammation of the skin or in asthma)
• medicines that may change the amount of METFORMIN ASCENDIS in your blood, especially if you have reduced kidney function (such as verapamil, rifampicin, cimetidine, dolutegravir, ranolazine, trimethoprime, vandetanib, isavuconazole, crizotinib, olaparib)
• Other medicines used to treat diabetes. METFORMIN ASCENDIS with iodinated contrasts agents It should be discontinue prior to, or at the time of the imaging procedure and not restarted until 48 hours after provided that renal function has been re-evaluated and found to be stable. METFORMIN ASCENDIS with alcohol Avoid excessive alcohol intake while taking METFORMIN ASCENDIS since this may increase the risk of lactic acidosis

What to do if you experience side effects

If you think you are having a side effect, the response depends on how severe it is. Use the warning signs above first — if any of those apply, treat it as urgent.

If the symptom is severe or frightening

Get medical help immediately. Call 10177 for an ambulance, or 112 from a mobile phone, or go to the nearest emergency department. Take the product and its packaging with you if you can.

If the symptom is mild but bothering you

• Write down what the symptom is, when it started, and how it relates to when you take the product
• Check the leaflet that came with the product to see whether the symptom is listed
• Speak to your pharmacist — for many questions this is the fastest route to a useful answer
• Contact the prescriber if the symptom is affecting your daily life or is not settling

You can also report a suspected side effect in South Africa. Reporting does not replace getting medical advice, and you do not need to be certain the product was the cause.

When to seek urgent medical help

Some symptoms need medical attention straight away rather than an appointment in a few days. Do not wait to see whether they settle.

Get same-day medical advice if you have

• A high fever, or a rash together with feeling generally unwell
• Yellowing of the eyes or skin, or unusually dark urine
• Unusual bruising or bleeding that you cannot explain
• Severe or persistent vomiting or diarrhoea, especially if you cannot keep fluids down
• A sudden change in mood, or thoughts of harming yourself
• Any symptom that is rapidly getting worse

How to report a suspected side effect in South Africa

South Africa has an official system for reporting suspected side effects, run by the South African Health Products Regulatory Authority (SAHPRA). Reports from the public and from healthcare professionals are how safety signals get detected after a product is already in use.

Who can report

Anyone can report — you do not have to be a healthcare professional, and you do not need to prove that the product caused the problem. A suspicion is enough. Patients, caregivers and family members can all submit a report.

What to have ready

• The name of the product, its strength and form, and the batch number if you have it
• Why it was being used, and when it was started and stopped
• What the suspected reaction was, when it began, and how long it lasted
• Any other medicines, supplements or remedies being used at the same time
• Basic details about the person affected — age and sex are usually enough

How to report

SAHPRA accepts adverse reaction reports through its e-Services reporting system and through the Med Safety mobile app. Healthcare professionals can also report through the same routes. Current forms and access points are published on the SAHPRA site.

• SAHPRA Health Products Vigilance — the main vigilance and reporting hub
• SAHPRA e-Services — current adverse reaction reporting access

For a fuller walkthrough see how to report an adverse drug reaction.

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