Antipsychotics, weight gain and metabolic monitoring

The MHRA notes that people with schizophrenia are three times more likely to die prematurely from natural causes, mainly cardiovascular disease, than people without mental health disorders. Smoking, diet, low activity and family history add to the baseline risk. Medicine-related weight and metabolic changes pile onto that.

The MHRA also noted that people with schizophrenia are undertreated for metabolic disorders, so the practical message is to look for problems routinely rather than wait for symptoms. This applies to everyone on antipsychotics, including older first-generation drugs, even though the data link the metabolic effects chiefly to some second-generation drugs.

The MHRA states that some atypical antipsychotics are associated with significant weight gain (more than 7 per cent of baseline), dyslipidaemia and hyperglycaemia, with clozapine, olanzapine and quetiapine especially implicated. The NHS page on olanzapine lists weight gain and increased appetite as a side effect and says olanzapine can raise blood sugar, sometimes leading to diabetes, affecting fewer than 1 in 100 people. It adds that long-term use can affect cholesterol.

NICE tells prescribers to discuss metabolic effects, including weight gain and diabetes, alongside movement, heart rhythm and hormonal effects when helping a person choose an antipsychotic. Individual drugs differ, and so do individual reactions, which is why people and prescribers weigh benefits for the mental illness against physical side effects.

NICE recommends baseline measurements before starting an antipsychotic and then structured follow-up. The figures below come directly from the NICE schedule for psychosis and schizophrenia in adults.

NICE advises offering a combined healthy eating and physical activity programme to people with psychosis or schizophrenia, especially those taking antipsychotics. If weight gain is rapid or excessive, or lipids or glucose are abnormal, services should offer interventions in line with NICE guidance on obesity, cardiovascular risk and diabetes prevention.

The NHS suggests for olanzapine that eating a balanced diet without increasing portion sizes, avoiding high-calorie snacks, eating fruit and vegetables between meals and regular exercise help keep weight stable. When cholesterol rises, a cholesterol-lowering medicine may be offered.

Prescribers may also consider the dose, a switch to a drug with a smaller metabolic effect, or other changes. Such decisions are made together with the person, because a medicine that controls symptoms well may be worth keeping. NICE also asks teams to offer help to stop smoking, with the caution that stopping smoking can change levels of clozapine and olanzapine and so needs coordination.

Excessive thirst, passing a lot of urine, tiredness and unexplained weight loss can signal high blood sugar rather than the weight gain more often expected. Rapid weight gain between scheduled reviews is also worth raising early, since catching it within weeks is easier than reversing it after a year.

Separately, the NHS lists serious reactions to olanzapine, including a high temperature with muscle stiffness, which need emergency care. Report any suspected side effect to your prescriber and, if you wish, through the MHRA Yellow Card scheme.

NICE asks that results be sent to the care coordinator and psychiatrist and recorded in notes, and that trusts audit monitoring through board-level indicators. In practice, secondary care and the GP agree who performs each check. If you are unsure whether your checks are due, ask your community mental health team or practice nurse, and keep a personal record of your weight and blood results.