Metformin Side Effects
Metformin Side Effects are most pronounced in those with compromised kidney function although even those who have healthy kidneys should be aware of other potential metformin side effects. Metformin side effects range from the most commonly experienced gastrointestinal discomfort to more serious effects like hypoglycemia. In addition there are adverse indications for specific groups of users including women, morbidly obese individuals and those with specific health problems and/or contraindications.
Metformin is commonly prescribed to treat type II diabetes, sometimes in conjunction with insulin. It is a front line prescription drug for the treatment of diabetes but the number of metformin side effects experienced means it is not the drug of choice for everyone. Specifically, some international medical health organizations have the following warnings with regard to Metformin side effects:
Non-specific metformin side effects including anorexia, hyperpnoea, altered consciousness
Anorexia, nausea, vomiting, altered level of consciousness, hyperpnoea, abdominal pain and thirst may be signs and symptoms of biguanide-induced lactic acidosis which are moderately severe metformin side effects. When these symptoms are nonspecific doctors may suspect lactic acidosis in patients presenting with acidosis and who are taking metformin. Significant mortality has been associated with biguanide-induced lactic acidosis.
Dosages beyond 1.7g/day poses additional risk
Caution is advised when increasing the daily dosage of metformin beyond 1.7g, especially in the elderly and those with mild renal disease who may suffer more severe metformin side effects. A metformin dosage of 850mg twice a day or 500 mg three times a day usually provides sufficient diabetic control.
Biguanide interference from raised lactate production & lowered clearance
Lactic acidosis appears to result from biguanide interference from metformin. This causes an increase in production and a decrease in clearance of lactate which leads to increased cellular lactate levels. This is a problematic metformin side effect because intracellular redox potential then shifts from aerobic to anaerobic metabolism. A resulting decrease in pyruvate carboxylase activity can also decrease hepatic metabolism of lactate.
Not recommended operative periods
Increased risk factors for metformin side effects associated with lactic acidosis include those patients with sepsis, high dosage prescriptions, increased age and/or dehydration. In situations where dehydration is likely, such as fasting for surgery or contrast radiography, it is recommended that metformin be stopped at least 48 hours prior to the procedure or upon admission for an emergency procedure. The medication should not be recommenced until the patient has fully recovered and is eating and drinking normally. The glucose levels of patients in catabolic states should be closely monitored and short-term insulin therapy used as an alternative to metformin in the interim.
Contraindicated for patients with renal disease
Patients with renal problems are advised to seriously consider alternatives as the potential for serious metformin side effects is substantially increased. Ninety percent of metformin is excreted unaltered by the kidneys and consequently lactic acidosis sometimes occurs in patients with renal deficiency. Significant renal impairment is an important consideration in determining whether or not a patient should be prescribed this drug. Even mild renal disease increases the risk of lactic acidosis. Because lactic acidosis is a metformin side effect the drug is also contraindicated for patients with hepatic disease, myocardial infarction, cardiac failure, pulmonary disease and/or alcoholism.
Metformin lactic acidosis side effect can be fatal
Although relatively uncommon the most serious Metformin side effect is lactic acidosis as it has proved fatal in patients with predisposing factors.
What all this means in plain English is that metformin is a useful medication for obese, non-insulin dependent diabetics whose glycaemia isn’t controllable with sulphonylurea monotherapy. Patients should however discuss metformin use with their doctors because in addition to the tolerable and acceptable metformin side effects, there are a number which pose a more serious risk. Patients, particularly those who may be at risk, should consider these more serious metformin side effects before considering the drug for treatment. For those who are at low risk of metformin side effects the drug is an effective means of controlling type II diabetes.
Metformin side effects may also include less severe reactions which range from headache to diarrhea. These metformin side effects are relatively minor and most can be treated with additional medication. Age, gender and psycho-social factors will also have an impact on if, and how, metformin side effects are experienced. There are specific information and warnings available for these groups and individuals with regard to predisposition and care regarding potential metformin side effects.
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