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Side Effects of Risperidone (Risperdal)


Description: Risperidoneis classified as an atypical antipsychotic medication. Also sold under the brand Risperdal, it is indicated to treat schizophrenia, as well as acute mania, agitation, and other conditions. Antipsychotic medications work to block the receptors in the brain’s dopamine pathways, which is thought to play a role in the pathogenesis of psychosis.

Black Box Warning for Risperdal

The FDA has issued black box warning on risperidone for numerous and potentially fatal adverse reactions. Among these, neuroleptic syndrome from risperidone is a risk, although rare, according to the Risperal drug label as reported by the Food and Drug Administration (Sept 2009). It is characterized by muscle rigidity, fever, altered mental status, and autonomic dysfunction symptoms such as dizziness or fainting upon getting up, hypotension, or an inability to alter heart rate with exercise, or exercise intolerance. Risperidone side effects also can include fatal cardiac arrhythmia in individuals who are susceptible based on their genetics.


Other serious side effects which constitute a medical emergency include tremor, restless muscle movements in your eyes, jaw, tongue, or neck, dizziness, fainting, fast or pounding heartbeat, seizure, pale skin, easy bruising, flu symptoms, and very stiff (rigid) muscles, high fever, sweating, confusion, or fast or uneven heart rate.

Common Side Effects for Risperdal

According to the Risperal drug label as reported by the FDA (Sept 2009), common and less serious side effects of risperidone include:

  • Dizziness
  • Drowsiness
  • Fatigue
  • Fever
  • Sleep problems (insomnia)
  • Nausea
  • Vomiting
  • Stomach pain
  • Constipation
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Weight gain
  • Feeling hot or cold
  • Headache
  • Dry mouth
  • Restlessness
  • Anxiety
  • Understand Your Risks with the Rxight® Genetic Test

    The most advanced platform that makes testing possible is the Rxight® pharmacogenetic testing from MD Labs. With one cheek swab, the Rxight® genetic test from can determine your genetic susceptibility to over 200 drugs and over-the-counter products. This means better, more individualized medical care for you, the patient.
    Armed with the knowledge of your Rxight® test result, you could be experiencing fewer, potentially dangerous, side effects from risperidone and other drugs you may take in the future.

    How Does Pharmacogenetic Testing Work?

    Pharmacogenetics emerged as a field in its own right after the human genome was sequenced. One ultimate goal of pharmacogenetics research is to determine the variations in every gene involved in drug metabolism in the human body. It is possible to reduce the side effects you experience with Risperidone and many other drugs by selection of the proper dose or dosing schedule.


    Pharmacogenetics research determined that there is wide variation among people in the genes that code for drug metabolism enzymes (proteins that ‘break up’ its partner molecule). So-called “fast metabolizers” are able to break the molecular bonds quickly, thus reducing the likelihood of developing side effects, but increasing the likelihood of not deriving therapeutic benefit at standard doses. In contrast, “slow metabolizers” break the molecular bonds more slowly than normal, making these patients susceptible to toxicity and drug side effects.


    Contributors to this Article:
    Michael Sapko, MD, PhD; Deborah Kallick, PhD, Medicinal Chemistry


    Read more about Rxight® genetic testing for drug metabolism