Clozapine is a schizophrenia drug that can cause constipation. Doctors usually prescribe it when other schizophrenia medications don’t work for you.

Keep reading to learn more about constipation caused by clozapine, including what you can do to manage it.

Clozapine’s effects on digestion are not wholly understood. With that said, there are several likely explanations as to why it causes constipation.

Firstly, clozapine modulates the effects of key neurotransmitters, including dopamine and serotonin. While both play an important role in psychological health, they also influence key biological functions, including digestion.

Serotonin, in particular, triggers the muscle contractions that help move waste matter through your gut, known as peristalsis. Clozapine can disrupt this process.

In addition, clozapine affects the functioning of the parasympathetic nervous system, which is also involved in peristalsis.

Symptoms of constipation

You might be constipated if you have fewer bowel movements after starting clozapine. Other symptoms of constipation include having to strain and push to have a bowel movement, or passing stool that’s dry or hard.

Constipation can also cause abdominal pain, bloating, and gas. You might feel uncomfortably full even after you have a bowel movement.

Sometimes, severe constipation leads to intestinal obstruction, a condition in which a partial or total blockage prevents the movement of waste matter through the bowels.

Antipsychotics are a class of drugs used to treat key symptoms of schizophrenia, including delusions, hallucinations, and paranoia. Healthcare professionals classify clozapine as a second-generation or atypical antipsychotic. The brand names available include Cloazril, Fazaclo ODT, and Versacloz, along with generics.

It’s FDA-approved for treating schizophrenia, but only when other first-line schizophrenia drugs don’t help relieve symptoms. In other words, doctors prescribe clozapine for treatment-resistant schizophrenia.

One of the reasons why healthcare professionals don’t prescribe clozapine right away is that it carries some risks. According to research, some possible side effects of clozapine include:

Constipation is a common side effect of clozapine. It affects approximately 15% to 60% of people who take this drug. It’s more likely to affect people who:

  • just started taking clozapine
  • take a high dose
  • don’t drink enough water
  • take other drugs or supplements that can cause constipation

Constipation can lead to serious complications. It’s typically your doctor’s responsibility to help you weigh the risks and benefits of taking clozapine, including whether you may be more likely to experience constipation. Be sure to speak up if you worry about how clozapine might affect your digestion.

Constipation can seriously affect your quality of life. If you experience mild to moderate constipation while taking clozapine, try the following to ease your symptoms:

  • Make lifestyle changes. There are many things you can try to relieve constipation without using medication. Small changes — like taking a walk after breakfast or snacking on fruits and vegetables — can go a long way.
  • Try a fiber supplement. Besides eating fiber-rich foods or adding bran to your cereal, you can also increase your dietary fiber with an over-the-counter (OTC) supplement.
  • Use laxatives with caution. Laxatives are a type of medication that can help you have a bowel movement. While they’re effective once in a while, they aren’t meant to be used on a long-term basis to help you pass stool due to the risk of side effects. Talk with your doctor or pharmacist about constipation treatment options.
  • Don’t hold in bowel movements. It’s important to listen to your body when you need to go to the bathroom, even if you’re not at home or busy with something else.
  • Talk with your doctor. Your doctor can be your advocate. It’s important not to wait until constipation is a major problem to have a conversation about it.

Note that mild to moderate constipation means that you still have bowel movements, but you’re not quite as regular as before. Always get medical attention for severe constipation.

Severe constipation can have serious consequences. It’s better to get treatment early instead of waiting until constipation causes complications. Although you might feel embarrassed discussing your bowel movements, your doctor can help you.

Consider making an appointment with your doctor if you have any of the following:

  • hard, dry, or lumpy stool
  • no bowel movements for 3 to 4 days
  • stool that slips out between bowel movements
  • symptoms of constipation that affect your well-being and day-to-day life

In severe cases, constipation requires urgent medical attention. Go to the emergency room if you experience any of the following:

  • abdominal bloating (distention) with intense stomach pain
  • rectal bleeding
  • inability to pass gas (flatus)
  • vomiting

If you have a prescription for clozapine, you can take steps to prevent constipation. Try the following:

  • Increase your fiber intake. Fiber is a carbohydrate that occurs naturally in foods like fruit, vegetables, and brown or whole grains. It helps to maintain regular bowel movements.
  • Avoid foods that can back you up. Certain foods can make constipation worse, for example milk and dairy products, red meat, and white bread, rice, or pasta.
  • Stay hydrated. Taking in adequate fluids helps keep your stool soft, making it easier to pass. Try sipping water throughout the day to stay regular.
  • Exercise regularly. Moderate exercise can be beneficial for your digestive health. Try incorporating activities you enjoy — like walking, dancing, or swimming — into your daily routine.
  • Manage stress. Stress sometimes worsens constipation. You can balance sources of stress in your life with relaxing activities, like yoga, breathing exercises, or meditation.
  • Maintain a routine. Sitting on the toilet around the same time every day — for instance, after eating breakfast — may lower your risk of constipation.

Clozapine is an atypical antipsychotic medication that healthcare professionals prescribe when other schizophrenia treatments don’t work. Constipation is a common side effect.

If you take clozapine, be sure to discuss how to manage constipation with your doctor. Your doctor can provide information about diet and lifestyle changes, along with OTC and prescription medication, to help improve symptoms associated with constipation.