While Risperdal can be effective in treating these disorders, you should be aware of the potential side effects before starting treatment. While many of the side effects are manageable, others may be serious and, in rare cases, life-threatening.
Common Side Effects
Risperdal can cause side effects for a variety of reasons. Because the drug has antihistaminic properties (similar to older antihistamine drugs), it may have a sedating effect in some people. It also acts as an alpha-adrenergic blocker, meaning that it interferes with certain hormones that regulate blood flow and blood pressure.
Risperdal also has anticholinergic effects that can alter how smooth muscles (those that make up the internal organs) function.
Because of these properties, Risperdal may cause the following side effects in at least one percent of users:
- Amenorrhea (absent period)
- Arthralgia (joint pain)
- Asthenia (physical weakness and lack of energy)
- Blurred vision
- Epistaxis (nosebleeds)
- Dyspnea (shortness of breath)
- Excessive salivation
- Galactorrhea (milky breast discharge)
- Gynecomastia (male breast enlargement)
- Hirsutism (abnormal hair growth in women)
- Increased appetite
- Myalgia (muscle pain)
- Nausea and vomiting
- Nasal congestion
- Painful intercourse in women
- Retrograde ejaculation (ejaculation of semen into the bladder rather than out of the body)
- Seborrhea (a scaly, patchy skin condition)
- Somnolence (sleepiness or drowsiness)
- Sore throat
- Sleep disturbances
- Suicidal thoughts
- Weight gain
- Upper abdominal pain
- Upper respiratory tract infection
- Urinary incontinence
- Xerostomia (dry mouth)
Extrapyramidal Side Effects
Extrapyramidal side effects (EPS) are those that affect the central nervous system and cause movement problems. EPS can affect as many as one of every four people who take Risperdal, although most cases are relatively mild.
Other than previous history of EPS, there is no way to know in advance whether you'll experience extrapyramidal side effects or not.
Types of EPS
Tardive dyskinesia is among the most common EPS experienced by Risperdal users. It is characterized by involuntary and repetitive movements, including those of the face, mouth, tongue, arms, or legs. These may include lip-smacking, grimacing, making chewing motions, rocking, rotating the ankles or legs, marching in place, sticking out the tongue, or making repetitive sounds such as humming or grunting.
Other types of EPS include:
- Akathisia (a feeling of inner restlessness and inability to stay still, often referred to as the "rabbit syndrome")
- Akinesia (loss or impairment of voluntary movement)
- Dystonic reactions (intermittent and involuntary contractions of the muscles of the face, neck, trunk, pelvis, and extremities)
- Parkinsonism (a group of neurological disorders that cause movement problems similar to Parkinson's disease, including tremors, slow movement, and stiffness)
The risk of EPS is largely dose-dependent. Similarly, the type of formulation you take can also influence your risk.
- Oral formulations of Risperdal are associated with a two percent to 12 percent risk of tremors, while intramuscular injections carry a three percent to 24 percent risk of the same.
- Tardive dyskinesia will affect anywhere from two percent to six percent of Risperdal users, depending on the formulation.
- Parkinsonism can affect as few as six percent to as many as 28 percent of users.
It is important to advise your doctor if you experience any involuntary muscle movements or have a loss of muscle control while taking Risperdal. If left untreated, conditions like tardive dyskinesia may become permanent.
Serious Side Effects
On rare occasions, exposure to atypical antipsychotics may result in a potentially life-threatening reaction known as a neuroleptic malignant syndrome (NMS). It is a condition characterized by the following symptoms:
- Altered mental state
- High fever (over 100.4 F)
- Loss of bladder control
- Muscle rigidity
- Profuse sweating
- Respiratory problem
- Tachycardia (rapid heartbeat)
Once symptoms appear, they tend to progress rapidly and can persist for anywhere from eight hours to over a month. For reasons unknown, NMS tends to affect men under 40 more than any other group.
NMS is considered a medical emergency and can lead to death if left untreated. Treatment would be administered in an intensive care unit, often with mechanical ventilation, intravenous fluids, and a variety of medications used to reduce muscle rigidity, agitation, and other symptoms.
Even with treatment, as many as 10 percent of NMS cases will result in death.
Other Serious Complications
Other rare but potentially life-threatening side effects may occur with Risperdal use. Most are associated with either overuse or long-term use of the drug.
- Diabetic ketoacidosis (a dangerous build-up of acids in the blood)
- Pancreatitis (inflammation of the pancreas)
- Pulmonary embolism (the formation of a blood clot in the lungs)
- Sudden cardiac death
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Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Thomson SR, Chogtu B, Bhattacharjee D, et al. Extrapyramidal symptoms probably related to risperidone treatment: a case series. Ann Neurosci. 2017;24(3):155-163. doi:10.1159/000477153
Berman, B. Neuroleptic Malignant Syndrome: A Review for Neurohospitalists. Neurohospitalist. 2011;1(1):41-7. doi:10.1177/1941875210386491
Divac, N.; Prostran, M.; Jakovcevski, I. et al. Second-Generation Antipsychotics: Extrapyramidal Adverse Effects. BioMed Res Int. 2014; DOI: 10.1155/2014/656370.
Muench, J. and Hamer, A. Adverse Effects of Antipsychotic Medications.Am Fam Physician. 2010;81(5):617-622.
U.S. Food and Drug Administration. Full Prescribing Information: Risperdal (risperidone).Daily Meds. Silver Spring, Maryland; updated April 30, 2018.
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