Bysanti Side Effects: What to Expect and How to Manage Them

Medically Reviewed by Beth Johnston, BCPS, PharmD on March 22, 2026

Bysanti (milsaperidone) is prescribed to treat mental health conditions, including bipolar disorder and schizophrenia. Like most medicines, Bysanti may cause side effects. Some are more common than others.

Keep reading to learn about possible Bysanti side effects, what you can do to help prevent them, what to do if they happen, and when to tell your health care provider.

This article does not include all possible side effects of Bysanti. Tell your health care provider if you have side effects that are ongoing or bother you, even if they are not listed.

Common Bysanti side effects may include:

  • Dizziness or lightheadedness
  • Dry mouth
  • Tiredness or drowsiness
  • Stuffy nose
  • Fast heartbeat
  • Weight gain

In most cases, these side effects are temporary and often improve on their own. However, contact your health care provider if you experience symptoms that feel severe or last longer than a few weeks. Do not stop taking Bysanti unless your provider recommends it.

Potentially serious Bysanti side effects are less common but may include:

  • Changes in heart rhythm
  • Very low blood pressure when standing, which may cause dizziness, fainting, or falls
  • Seizures
  • Unusual muscle movements or stiffness
  • Swallowing problems
  • An unwanted erection that lasts several hours and may be painful
  • Allergic reactions

If you think you may be having a serious side effect, contact your health care provider right away. Severe symptoms, such as fainting, chest pain, or trouble breathing, may require urgent medical care.

Some side effects can be managed with simple strategies. As mentioned, this article is not a complete list of Bysanti side effects.

Next, we’ll describe six Bysanti side effects in detail, including steps to help prevent or manage them.

1. Dizziness or lightheadedness

Dizziness is one of the most common side effects of Bysanti. Hence, Bysanti treatment is started with a low dose and increased over the first several days to help your body adjust to the medicine.

Possible symptoms include:

  • Feeling lightheaded
  • Feeling unsteady when standing
  • Fainting or feeling like you might pass out

This can happen because Bysanti may lower blood pressure, especially when standing up.

Here are some strategies that may help:

  • Stand up slowly when rising from sitting or lying down.
  • Sit or lie down if you begin to feel dizzy.
  • Drink fluids throughout the day.

Tell your health care provider if dizziness becomes severe or does not improve. They may lower your dose or review other medicines that could worsen this effect.

2. Sleepiness

Drowsiness or feeling unusually tired may occur with Bysanti. Medicines that affect the brain and nervous system often cause this effect.

Possible symptoms include trouble staying alert during the day and slower thinking or reaction time. You should also avoid driving or operating machinery until you know how Bysanti affects you.

These symptoms may improve after your body gets used to the medicine. To help support healthy energy, get plenty of sleep and maintain a regular sleep schedule. Try to include nutrient-rich foods in every meal.

If drowsiness becomes bothersome or interferes with daily activities, contact your health care provider. They may adjust your dose or review other medicines that may contribute to tiredness or drowsiness.

3. Dry mouth

Dry mouth is another common side effect of Bysanti.

Possible symptoms include:

  • A sticky or dry feeling in the mouth
  • Increased thirst
  • Trouble swallowing dry foods

Mild dry mouth can often be managed at home. Possible strategies include:

  • Sip water throughout the day to moisten your mouth.
  • Chew sugar-free gum or suck on sugar-free candies or ice chips.
  • Try over-the-counter (OTC) products for dry mouth, such as a mouth rinse.
  • Maintain good oral hygiene, including regular brushing, flossing, and dental visits.
  • Avoid mouthwashes that contain alcohol.

If dry mouth becomes severe or does not improve over time or with any of the above suggestions, tell your health care provider.

4. Fast heartbeat

Bysanti may cause your heart to beat faster than usual. This was one of the most common side effects in studies and may be more noticeable at higher doses.

If you notice a fast or irregular heartbeat, contact your health care provider. They may need to check your symptoms and decide whether changes to your treatment plan are needed. Seek medical care right away if symptoms occur along with dizziness, fainting, or chest pain.

5. Weight gain

Bysanti may cause weight gain. Some antipsychotic medicines, including Bysanti, can affect your metabolism, which is the body’s process of making energy. These metabolic changes may lead to weight gain and other changes, such as increased blood sugar and cholesterol.

Healthy lifestyle habits may help reduce the risk of weight gain. Here are some strategies that may help:

  • Follow a balanced eating pattern that emphasizes fruits, vegetables, whole grains, and healthy fats.
  • Limit foods high in saturated fat or sugars.
  • Stay physically active with regular exercise, such as walking or other moderate activity.

When increasing physical activity, it is important to be aware that medicines like Bysanti may affect your body’s ability to regulate temperature. Intense exercise, exposure to extreme heat, and dehydration may raise your risk of overheating. To stay safe while exercising, be sure to drink enough fluids and avoid excessive heat.

If you gain a lot of weight, your health care provider may adjust your treatment plan. They may prescribe medicines to help manage weight, blood sugar, and/or cholesterol.

6. Stuffy nose

Nasal congestion is another possible side effect of Bysanti. Symptoms may include a stuffy nose, runny nose, sinus pressure, or trouble breathing through your nose. 

The following strategies may help with a stuffy nose:

  • Stay hydrated to help thin mucus.
  • Use a humidifier or breathe in warm steam.
  • Try saline nasal sprays or rinses.

If nasal congestion becomes bothersome or does not improve, tell your health care provider. They may suggest OTC medicines, such as a decongestant, for symptom relief.

Can Bysanti cause long-term side effects?

Possibly. Some side effects improve over time as your body adjusts to treatment. However, Bysanti may cause ongoing side effects such as weight changes, new or worsened diabetes, or movement problems. Your health care provider can help manage long-term side effects.

Does Bysanti cause hair loss?

Hair loss is not a known side effect of Bysanti. It was not reported as a side effect during studies.

Other factors can contribute to hair loss, such as aging, stress, and not getting enough of certain vitamins and nutrients. If you have hair loss that bothers you while taking Bysanti, let your health care provider know. They can help identify the cause and recommend next steps.

You can reduce your risk of side effects by taking Bysanti exactly as prescribed. 

  • Consider using a journal or health app to keep track of new or changing symptoms.
  • Attend all medical appointments and lab tests while taking Bysanti. 
  • Do not increase your dosage sooner than prescribed. Follow the recommended schedule, and do not change your dose without talking to your prescriber first.

Report side effects to your health care provider, especially if they do not improve or start to interfere with daily activities. Your health care provider can review your symptoms and help decide whether changes to your treatment plan are needed.

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