[10] Common side effects include weight gain, drowsiness, fatigue, insomnia, dry mouth, constipation, elevated prolactin levels, and restlessness.

[2][11] Serious side effects may include the potentially permanent movement disorder tardive dyskinesia, as well as neuroleptic malignant syndrome, an increased risk of suicide, and high blood sugar levels.

[18] A 2011 review concluded that risperidone is more effective in relapse prevention than other first- and second-generation antipsychotics with the exception of olanzapine and clozapine.

[19] A 2016 Cochrane review suggests that risperidone reduces the overall symptoms of schizophrenia, but firm conclusions are difficult to make due to very low-quality evidence.

Data and information are scarce, poorly reported, and probably biased in favour of risperidone, with about half of the included trials developed by drug companies.

[7][33] Some authors recommend limiting the use of risperidone and aripiprazole to those with the most challenging behavioral disturbances to minimize the risk of drug-induced adverse effects.

[35] While antipsychotic medications such as risperidone have a slight benefit in people with dementia, they have been linked to a higher incidence of death and stroke.

[36] Because of this increased risk of death, treatment of dementia-related psychosis with risperidone is not FDA-approved and carries a black box warning.

[7] However, many other jurisdictions regularly use it to control severe aggression and psychosis in those with dementia when other non-pharmacological interventions have failed and their pharmaceutical regulators have approved its use in this population.

[37][38] Risperidone has demonstrated clinical benefit as an augmentation agent in the management of (unipolar) non-psychotic treatment-resistant depression alongside antidepressant treatment.

Such usage occurs off-label in most jurisdictions and the risk of adverse effects (e.g., weight gain, movement disorders) must be carefully weighed against the clinical benefit.

[41] Risperidone has proven to be effective in treatment with attention deficit hyperactivity disorder (ADHD), especially in cases of aggression[42][43] or with another mental condition.

[45] Common side effects include movement problems, sleepiness, dizziness, trouble seeing, constipation, and increased weight.

[2] Serious side effects may include the potentially permanent movement disorder tardive dyskinesia, as well as neuroleptic malignant syndrome, an increased risk of suicide, and high blood sugar levels.

It can also cause sexual side effects, galactorrhoea, infertility, gynecomastia, and, with chronic use, reduced bone mineral density leading to breaks, all of which are associated with increased prolactin secretion.

[78] In August 2012, J&J agreed to pay $181 million to 36 US states to settle claims that it had promoted risperidone and paliperidone for off-label uses including for dementia, anger management, and anxiety.

[79] In November 2013, J&J was fined $2.2 billion for illegally marketing risperidone for use in people with dementia and paying kickbacks to prescribing physicians and nursing home pharmacies.

[83] In October 2019, a jury ordered J&J to pay $8 billion in punitive damages to a Pennsylvania man who had grown breasts during adolescence.