Risperidone injection: what it treats, dosing, and side effects
Last updated September 7, 2026.
**Risperidone injection is a long-acting form of risperidone, a second-generation (atypical) antipsychotic given as a shot every 2 weeks, every month, or every 2 months instead of a daily pill.** Risperidone blocks dopamine D2 and serotonin 5-HT2A receptors in the brain, which reduces hallucinations, delusions, and disorganized thinking and steadies mood. The long-acting shot releases the drug slowly, so blood levels stay steady between visits. The most important safety point is that these injections are not approved for behavior problems in older adults with dementia, because antipsychotics raise the risk of death in that group.
What does it treat?
Risperidone injection treats schizophrenia in adults, and Risperdal Consta is also approved for maintenance treatment of bipolar I disorder, either alone or added to lithium or valproate. Clinicians reach for the shot when someone has responded to oral risperidone but keeps relapsing because daily pills are hard to take on time, or when a person prefers not to think about medication every day. The target symptoms are hearing voices, fixed false beliefs, paranoia, disorganized speech, and the mood swings and irritability of bipolar I. Brand forms in the US include Risperdal Consta and Rykindo, given into the muscle every 2 weeks, and Uzedy, given under the skin monthly or every 2 months. There are no combination products; risperidone injection is a single-ingredient medicine, though it is often used alongside a mood stabilizer in bipolar I.
How do you take it?
A trained clinician gives the injection; you never inject it yourself. Risperdal Consta is 25 mg into the gluteal or deltoid muscle every 2 weeks, with some people doing better on 37.5 mg or 50 mg, and the label ceiling is 50 mg every 2 weeks with dose increases no more often than every 4 weeks. Because Consta releases almost nothing for the first 3 weeks, you keep taking oral risperidone or another antipsychotic for those first 3 weeks; Rykindo needs only 7 days of oral cover. Uzedy is injected under the skin of the upper arm or abdomen, commonly 50 mg, 75 mg, 100 mg, or 125 mg once monthly, with every-2-month strengths available, and it does not need oral supplementation. Food, alcohol timing, and meals do not affect the shot, so there are no food rules. If you miss an appointment, call the clinic that day to reschedule rather than waiting for the next cycle, since a long gap can mean restarting with oral cover. Do not stop the injections on your own; call your prescriber if symptoms return, if you feel restless and unable to sit still, or if you develop stiff muscles, fever, or uncontrolled movements of the face or tongue.
Side effects to know
- Common: Common effects include sleepiness, weight gain, restlessness or an urge to keep moving, tremor or stiffness, dizziness when standing up, increased appetite, constipation, dry mouth, and soreness or a small lump at the injection site.
- Serious: Get medical help right away for high fever with rigid muscles, confusion, sweating, and a racing or irregular heartbeat (neuroleptic malignant syndrome), for repetitive uncontrolled movements of the tongue, lips, or face that do not stop (tardive dyskinesia), or for very high blood sugar with heavy thirst, frequent urination, and fruity-smelling breath. Also seek urgent care for fainting, a seizure, an erection lasting more than 4 hours, or signs of a severe allergic reaction such as swelling of the face, lips, or throat.
Who should not take it?
Do not use risperidone if you have had an allergic reaction to risperidone or paliperidone, and it should not be used to manage behavior in older adults with dementia-related psychosis. Talk with a clinician first if you have diabetes or high blood sugar, high cholesterol, heart disease, low blood pressure or fainting spells, a history of stroke, Parkinson disease or Lewy body dementia, seizures, a low white blood cell count, breast cancer or a high prolactin level, trouble swallowing, or kidney or liver disease. Carbamazepine and other strong enzyme inducers lower risperidone levels, while fluoxetine and paroxetine raise them, so doses often need adjusting; risperidone can also blunt the effect of levodopa and other dopamine agonists, and it adds to the sedating and blood-pressure-lowering effects of opioids, benzodiazepines, sleep aids, and blood pressure medicines. Skip alcohol or keep it minimal, since it increases drowsiness and the risk of falls. In pregnancy, especially the third trimester, exposure can cause tremor, stiffness, feeding trouble, or withdrawal signs in the newborn, so tell your clinician if you are pregnant or planning to be, and consider the National Pregnancy Registry for Atypical Antipsychotics at 1-866-961-2388. Risperidone passes into breast milk, so if you nurse, watch the baby for unusual sleepiness, poor feeding, jitteriness, or abnormal movements and report them.
When is it an emergency?
Call 911 for collapse, a seizure, trouble breathing, chest pain, or swelling of the face, lips, or throat with hives. Call 911 or go to an emergency room for fever above 100.4 F with muscle rigidity, confusion, and sweating, for fainting, or for an erection lasting more than 4 hours, which can permanently damage tissue. Signs of too much risperidone in the body include extreme drowsiness, slurred speech, a fast or irregular heartbeat, very low blood pressure, and severe muscle stiffness or twitching. For any suspected overdose, including an accidental extra dose given too soon, call Poison Control at 1-800-222-1222 right away, and call 911 if the person is unresponsive or struggling to breathe. Because the shot keeps releasing drug for weeks, overdose effects can last for days and usually need monitoring in a hospital.
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Common questions
What is the maximum dose of risperidone injection?
For Risperdal Consta, the label ceiling is 50 mg into the muscle every 2 weeks, and doses above that have not been shown to work better while causing more side effects. Most people start at 25 mg every 2 weeks, and increases happen no more often than every 4 weeks so the slow-release level can settle. Uzedy is dosed under the skin monthly, commonly 50 mg to 125 mg, or every 2 months at matched strengths. The right dose is the one that matches the oral risperidone dose you responded to, so never ask for an early or extra shot to catch up.
Can I drink alcohol on risperidone injection?
Alcohol adds to the drowsiness, dizziness, and low blood pressure that risperidone can cause, which raises your risk of falls and car crashes. There is no interaction that makes alcohol dangerous in a chemical sense, but the combined sedation is real and can last hours. Alcohol also worsens sleep and mood stability, which works against what the injection is doing. If you drink, keep it light and skip it entirely in the first weeks after a dose change.
Is risperidone injection safe during pregnancy or breastfeeding?
Risperidone crosses the placenta, and babies exposed in the third trimester can be born with tremor, stiffness, floppiness, sleepiness, feeding problems, or breathing trouble that usually clears in days. Untreated schizophrenia or bipolar I in pregnancy carries its own serious risks, so the decision is made with your prescriber rather than by stopping on your own. Because the injection stays in your system for weeks, plan ahead if you are trying to conceive. Risperidone appears in breast milk, so if you nurse, watch your baby for unusual sleepiness, poor feeding, jitteriness, or abnormal movements. You can enroll in the National Pregnancy Registry for Atypical Antipsychotics at 1-866-961-2388.
Do I need to take it with food?
No. Risperidone injection goes into muscle or under the skin, so it never passes through your stomach and food has no effect on how it is absorbed. Eat normally on injection day. The one food-related point worth tracking is weight and appetite, since risperidone commonly increases both, and your clinician should check your weight, blood sugar, and cholesterol at least yearly.
What happens if I miss my injection appointment?
Call the clinic the same day and get in as soon as possible; do not simply wait for the next scheduled date. Short delays of a few days usually mean you just get the shot late and continue on the original schedule. Longer gaps can drop your blood level enough that symptoms return, and with Risperdal Consta a gap beyond about 6 weeks generally means restarting with oral risperidone cover for the first 3 weeks. Never take extra oral risperidone on your own to fill a gap without asking your prescriber.
What drugs interact with risperidone injection?
Carbamazepine and other strong enzyme inducers such as phenytoin, rifampin, and phenobarbital lower risperidone levels and often require a higher injection dose, then a dose reduction when they are stopped. Fluoxetine and paroxetine raise risperidone levels and can increase stiffness, tremor, and sedation. Risperidone can reduce the benefit of levodopa and other Parkinson medicines, and it adds to sedation from opioids, benzodiazepines, sleep aids, and antihistamines. Blood pressure medicines combined with risperidone can cause fainting when you stand up. Give your prescriber a full list of everything you take, including over the counter products and supplements.