Note: This document contains side effect information about metformin. Some dosage forms listed on this page may not apply to the brand name Fortamet.
Applies to metformin: oral solution, oral tablets.
Warning
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Lactic Acidosis
- Lactic acidosis rare but potentially fatal.1 6 18 20 27 29 30 62 89 96 158 234 254 Increased risk of lactic acidosis in patients with renal impairment and advanced age.1 2 62 96 119 234 254 260 314 352 355 361
- Generally has occurred in diabetic patients with severe renal insufficiency and concomitant medical and/or surgical problems who were receiving multiple drugs; metformin plasma concentrations >5 mcg/mL often found in patients with lactic acidosis.1 2 3 20 50 62 64 76 96 123 158 164 165 234 254 314
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Periodically monitor renal function and use the minimum effective dosage.1 32 62 63 65 76 85 91 93 96 119 123 124 158 164 165 234 254 258 287 314 Withhold metformin promptly in patients with any condition associated with hypoxemia, sepsis, or dehydration.1 2 62 63 93 234 260 314 340 Avoid use in patients with clinical or laboratory evidence of hepatic impairment.1 2 63 65 85 91 93 156 158 234 254 314 352 355 Manufacturers state to temporarily discontinue metformin therapy before or at the time of an intravascular (e.g., IV, intra-arterial) iodinated contrast imaging procedure in patients with eGFR of 30–60 mL/minute per 1.73 m2 and in patients with a history of liver disease, alcoholism, or heart failure.1 234 254 330 336 352 355 610 Withhold metformin temporarily in patients undergoing surgery. 1 2 30 62 63 93 158 234 254 261 314 330 336 352 355 610 Concomitant drugs that may affect renal function, produce substantial hemodynamic changes, or alter metformin elimination should be used with caution.1 134 234 254
However, the American College of Radiology states that in patients with no evidence of acute kidney injury and eGFR ≥30 mL/minute per 1.73 m2, no need to discontinue metformin either before or following the administration of iodinated contrast media, nor is there a need to reassess the patient's renal function after the test or procedure.335
- Advise patients not to consume excessive amounts of alcohol, acutely or chronically.1 2 63 76 91 93 158 234 314 352 355
- If lactic acidosis occurs, discontinue metformin and institute general supportive therapy immediately.1 30 260 314 Treat as medical emergency, with immediate hospitalization and treatment required; prompt hemodialysis recommended.1 23 32 62 117 119 234 254 260 314 352 355
Side effects include:
Diarrhea, nausea, vomiting, abdominal bloating, abdominal cramping or pain, flatulence, anorexia.
For Healthcare Professionals
Applies to metformin: compounding powder, oral solution, oral suspension extended release, oral tablet, oral tablet extended release.
General
Gastrointestinal events such as nausea, vomiting, diarrhea, abdominal pain, and loss of appetite have been frequently reported during therapy initiation and resolve spontaneously in most cases.
Adverse events in the pediatric population appear to be similar in nature and severity to that published in adults.[Ref]
Metabolic
Common (1% to 10%): Hypoglycemia
Very rare (less than 0.01%): Lactic acidosis[Ref]
Gastrointestinal
Very common (10% or more): Diarrhea (53.2%), nausea/vomiting (25.5%), flatulence (12.1%)
Common (1% to 10%): Indigestion, abdominal discomfort, abnormal stools, dyspepsia, loss of appetite[Ref]
Hematologic
Very rare (less than 0.01%): Subnormal vitamin B12 levels[Ref]
Other
Common (1% to 10%): Asthenia, chills, flu syndrome, accidental injury[Ref]
Hepatic
Very rare (less than 0.01%): Liver function test abnormalities, hepatitis[Ref]
Cardiovascular
Common (1% to 10%): Chest discomfort, flushing, palpitation[Ref]
Dermatologic
Common (1% to 10%): Rash, nail disorder, increased sweating
Very rare (less than 0.01%): Erythema, pruritus, urticaria[Ref]
Endocrine
Frequency not reported: Reduction in thyrotropin (TSH) levels[Ref]
Immunologic
Very common (10% or more): Infection (20.5%)[Ref]
Musculoskeletal
Common (1% to 10%): Myalgia[Ref]
Nervous system
Common (1% to 10%): Lightheadedness, taste disturbances[Ref]
Psychiatric
Common (1% to 10%): Headache[Ref]
Respiratory
Common (1% to 10%): Rhinitis[Ref]
