What are the side effects of metformin?
Metformin causes gastrointestinal complaints such as diarrhoea, nausea and vomiting in a substantial proportion of users. Discuss with your doctor whether the dose can be built up gradually, or consider an alternative if the complaints persist.
Gastrointestinal complaints are the most common side effects of metformin. A randomised study in women with PCOS found that 31.6% experienced diarrhoea, 14.0% vomiting, 13.2% nausea, 11.4% loss of appetite and 8.8% stomach pain. Compared with placebo or acupuncture, these complaints occurred significantly more often.
How large the overall risk of side effects is was examined in a Cochrane review of women using metformin around the time of IVF. The metformin group had more than three times the chance of experiencing side effects compared with the placebo group. The researchers rated the certainty of this figure as low, but the direction is clear: metformin substantially increases the risk of side effects.
A rarer but more serious side effect is lactic acidosis: a build-up of lactic acid in the blood that can be life-threatening. The likelihood of this is small, but the risk does exist. People with poor kidney function are at higher risk, because metformin is then excreted less efficiently.
The gastrointestinal complaints can be partly reduced by taking metformin with a meal or by increasing the dose gradually. Nevertheless, the side effects are reason enough for some people to stop or switch to an alternative, which also explains why researchers are looking for agents with a comparable effect but fewer complaints.
All claims are based on studies in women with PCOS (RCTs and a Cochrane review). Whether the frequency of side effects is comparable in other groups (such as people with type 2 diabetes) cannot be determined from the available sources.
Does metformin help you stay healthy for longer?
Metformin can largely prevent diabetes in people with prediabetes or metabolic syndrome, and that brings real health benefits. Whether it also slows ageing in healthy people has not yet been demonstrated.
What do we really know about metformin and ageing?
In people with diabetes, metformin shows clear health benefits. Whether it also slows ageing in healthy people is being investigated by an ongoing study.
Can you take metformin without having diabetes?
Metformin has a reasonable evidence base for specific groups without diabetes (prediabetes, PCOS, overweight with insulin resistance), but as a general agent for healthy people, evidence from large randomised trials is entirely absent; always discuss use with your doctor.
What are the side effects and risks of retatrutide?
Retatrutide causes gastrointestinal complaints in many users and a temporary increase in heart rate; serious side effects were rare in the available studies, but long-term safety remains largely unknown. Slow dose escalation helps to limit complaints, but always discuss use with your doctor.
How does metformin work in your body?
Metformin lowers blood sugar primarily by causing the liver to produce less new glucose, without the risk of dangerously low blood sugar. Exactly how all the pieces of the mechanism fit together is not yet fully clear.
Does metformin help with weight loss?
Metformin helps with weight loss, but the effect is modest: expect a few kilograms, not a dramatic transformation. Lifestyle changes work better in the short term, but weight loss with metformin remains stable over the long term. Discuss it with your doctor if you want to know whether it suits your situation.