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Risperdal Side Effects

Weight gain, drowsiness, dizziness and nausea are the most common side effects of Risperdal (risperidone). Serious side effects include enlarged breast tissue, obesity, heart problems and diabetes, which lead experts to recommend alternative treatments for children who are stable but experiencing aggression or irritability.

Last Modified: September 5, 2023
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Common Side Effects of Risperdal

The most common side effect of Risperdal reported in clinical trials was insomnia. Anxiety, Parkinsonism (super brief definition), and other nervous disorders were also more common.

Common Risperdal side effects include:
  • Movement disorders (Parkinsonism, tremor, muscle contractions)
  • Pain in the extremities
  • Restlessness
  • Insomnia
  • Increased appetite
  • Dizziness
  • Headache
  • Indigestion
  • Constipation
  • Stomach pain
  • Nausea
  • Weight gain
  • Dry mouth
  • Hay fever
  • Anxiety
  • Fatigue
  • Sedation

Approved for treatment of schizophrenia, bipolar disorder and autism spectrum disorders, Risperdal caused a host of common side effects in clinical trials, including increased appetite, upper respiratory tract infection, vomiting and rash.

Although manufacturer Johnson & Johnson has not received FDA approval to market and sell Risperdal for attention deficit hyperactivity disorder (ADHD), sleep disorders, anxiety disorders and depression, doctors prescribe the drug for these “off-label” uses.

These side effects were observed most frequently in clinical trials and range from mild discomfort to severe adverse events that can last indefinitely. Prolonged use of the antipsychotic can lead to tardive dyskinesia and gynecomastia. The latter is a rare side effect that has cost the manufacturer billions of dollars in lawsuits.

Black Box Warning

In 2005, the FDA required Risperdal and other atypical antipsychotics to carry the agency’s strongest warning. The black box was added because of an increased risk of premature deaths of elderly people with dementia-related psychosis.

The warning says the death rate of these patients on the drug during a typical 10-week controlled trial was 4.5%, compared to 2.6% taking placebos. The causes of death varied. Most involved some type of cardiovascular failure or infection.

“Elderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death,” the drug’s label says.

Researchers examined this warning and published their findings in the Canadian Medical Association Journal in 2007. They found elderly patients on conventional antipsychotic medications face death risks that are comparable or even greater than elderly patients on atypical antipsychotics like Risperdal.

“Until further evidence is available, physicians should consider all antipsychotic medications to be equally risky in elderly patients,” researchers said.

The Effect of Prolactin

Prolactin is a hormone that controls sex drive in males. The pituitary gland produces prolactin, and the neurotransmitter dopamine controls the levels of the hormone.

Risperdal blocks dopamine’s action on the pituitary gland and can cause the levels of prolactin to increase and reach abnormal levels.

In women, prolactin stimulates breast development and breast milk production. When high levels of prolactin are present in males, those excessive levels can prompt similar processes, resulting in gynecomastia, excessive breast tissue growth, sometimes accompanied by galactorrhea (abnormal lactation).

In clinical trials involving 1,885 children and adolescents taking Risperdal, 43 boys experienced gynecomastia.

Since the U.S. Food and Drug Administration approved Risperdal in 1993, hundreds of boys have developed breasts that resemble those of women’s while on the medication. In some cases, boys’ breasts grow as large as “DD” cups.

According to an article published in the Journal of Clinical Psychiatry, elevated prolactin levels may occur in more than 90% of Risperdal users at some point during treatment. This effect, referred to as Risperdal-induced hyperprolactinemia, often persists throughout therapy and for some time after the drug is discontinued.

In children and adolescents, the overabundance of prolactin can cause:

  • Gynecomastia
  • Milky, nipple discharge in both males and females (galactorrhea)
  • Absence of periods in females
  • Delay in growth

Rising levels of prolactin may also cause sexual dysfunction. According to a 2022 article in StatPearls, sexual dysfunction may occur in 45% to 80% of males and 30% to 80% of females taking Risperdal.

Early Signs of Gynecomastia

Males who take Risperdal not only accumulate fat in their chest tissues, as can happen in overweight boys and men, but they also develop excess breast tissue. Growths typically begin as a small lump under the nipple. The nipple may become tender and gradually will grow larger.

The degree of enlargement can vary from one individual to another, and while gynecomastia most often occurs in both breasts, it can affect just one. When the condition strikes both breasts, each can be affected differently. One breast can grow larger than the other, leaving the patient with an even more uncomfortable social stigma. In some cases of gynecomastia, males produce breast milk.

Treating Gynecomastia

Mild to moderate cases of gynecomastia may resolve themselves with discontinuing the use of Risperdal. Switching to a safer, prolactin-sparing antipsychotic medication becomes an option at that point.

If enlarged breasts remain for a year or more, doctors may suggest surgery to normalize breast size. Many men and boys have had to undergo standard or laser-assisted liposuction, male breast reduction surgery or mastectomy to resolve male breast enlargement.

Movement Disorders

Risperdal is linked to muscular and neurological problems called extrapyramidal symptoms (EPS). These are uncontrolled movements that involve a series of short, quick movements of the limbs, head and tongue, or slow, painful, twisting movements that are repeated over and over. People may even make involuntary noises such as grunting.

Diagram showing extrapyramidal symptoms.

While most antipsychotic drugs come with a higher risk of these disorders, Risperdal and other atypical antipsychotics, the newer generation of antipsychotics, cause fewer cases of EPS.

For some patients who develop these conditions, they remain even after they stop taking the medication.

If a patient notices any loss of motion or control while taking these drugs, a doctor needs to address the problem before it becomes irreversible. Although addressing EPS often involves stopping treatment with antipsychotics, some patients may require continuation of Risperdal despite the presence of movement disorders.

Researchers don’t understand why or how antipsychotic medications cause these disorders. Some theories point to the way antipsychotics alter the levels of neurotransmitters like serotonin and dopamine in the brain.

Dopamine is responsible for regulating body movement, and it is possible that by altering dopamine levels, Risperdal can cause unnatural and involuntary movements. This may cause abnormal stimulation of the parts of the brain that signal muscles to move. In many cases, patients will have irreversible damage to receptors in the brain.

Tardive Dyskinesia and Tardive Dystonia

Tardive dyskinesia and the related tardive dystonia are two conditions that involve abnormal bodily movements. The risks of developing them and the likelihood they will become irreversible are believed to increase as the duration of treatment and the dose administered increase. There is no known treatment for established cases of tardive dyskinesia, although doctors may recommend discontinuing use of Risperdal in an attempt to lessen or stop symptoms completely.


In clinical trials, parkinsonism was listed as one of the most common adverse reactions to Risperdal in schizophrenia patients. When caused by a medicine, it is also referred to as secondary parkinsonism. This helps differentiate the condition from Parkinson’s disease.

Like tardive dyskinesia and dystonia, parkinsonism causes involuntary body movements. Elderly users are most susceptible.

Weight Gain

Weight gain is one of the most common side effects of Risperdal. In one study, patients gained an average of 4.6 pounds after 10 weeks of treatment. The FDA reports that patients on the drug had “a statistically significantly greater incidence of weight gain.”

Patients who experience any side effects while taking this drug should contact their doctors. They should not stop taking any medication without consulting a doctor, as this may result in withdrawal and a relapse of symptoms.

Pituitary Tumors

Risperdal can cause the pituitary gland to grow in size. This disrupts the production of hormones and can lead to the development of pituitary tumors.

One study published in the journal Pharmacotherapy analyzed the FDA’s adverse effect database and found that the drug accounted for 70% of all pituitary tumors. The researchers also said that there may be more cases but the adverse events are underreported.

While pituitary tumors are usually benign, they can cause other serious health problems, such as vision problems, internal bleeding, headaches and convulsions.

Pituitary gland close up rendering
Risperdal can cause the pituitary gland to increase in size leading to pituitary tumors.


Patients with schizophrenia are already at an increased risk of diabetes mellitus (Type 2 diabetes) compared with the general population. On top of this, studies suggest a relationship between antipsychotic use and high blood sugar incidents, known as hyperglycemia-related events. Patients on any antipsychotic should monitor their glucose levels.

Risperdal is associated with elevated blood sugar levels and diagnoses of Type 2 diabetes, including, in rare cases, extreme ketoacidosis (shortage of insulin) resulting in coma or death. Studies suggest that the risk of Type 2 diabetes is higher with atypical antipsychotics than with traditional antipsychotics.

Lawsuit Information
More than 13,000 Risperdal lawsuits have been filed against Johnson & Johnson. Learn about pending cases.
View Lawsuits

Heart Problems and Death

Numerous studies show Risperdal and other atypical antipsychotic drugs can interfere with the electrical impulses that regulate heart rhythm, causing cardiac arrhythmias that can lead to cardiac arrest and death.

Another rare but serious side effect is neuroleptic malignant syndrome (NMS), a life-threatening neurological condition that occurs in less than 1% of patients taking an antipsychotic medication.

In a 2009 study published in the New England Journal of Medicine, researchers found that users of atypical antipsychotic drugs had a rate of sudden cardiac death that was more than twice the rate for nonusers.

Arrhythmia (Irregular Heartbeat)

All antipsychotic drugs are associated with increased risk of arrhythmia, or irregular heartbeat.

A 2002 study evaluated risk of arrhythmia and cardiac arrest in schizophrenic patients treated with risperidone, clozapine, thioridazine or haloperidol between 1993 and 1996. According to the study, patients using these drugs had rates of arrhythmia and cardiac arrest between 1.7 and 3.2 times higher than that of a control group (even though members of that control group were older than the patients taking antipsychotic drugs). Death rates also were higher — 2.6 and 5.8 times higher.

Of the four drugs evaluated, Risperdal had the highest risk of cardiac arrest, arrhythmia and death, and surprisingly, that risk increased with lower doses of the drug.

Other heart issues associated with Risperdal include metabolic changes that can increase the risk of disease, such as hyperglycemia, diabetes, dyslipidemia and weight gain.

Please seek the advice of a medical professional before making health care decisions.