Clozapine Side Effects

An Introduction to Clozapine Side Effects
As with any medicine, side effects are possible with clozapine (Clozaril®, FazaClo®). However, not everyone who takes the drug will experience side effects. In fact, most people tolerate it quite well. If side effects do occur, in most cases, they are minor and either require no treatment or are easily treated by you or your healthcare provider.

(This article covers many, but not all, of the possible side effects with clozapine. Your healthcare provider can discuss a more complete list with you.)
Common Side Effects of Clozapine
Clozapine has been studied thoroughly in clinical trials.
In these studies, the side effects that occur in a group of people taking the drug are documented and then compared to the side effects that occur in another group of people not taking the medicine. As a result, it is possible to see what side effects occur, how often they appear, and how they compare to the group not taking the medicine.

In these studies, the most common clozapine side effects included:

• Increased salivation -- in up to 48 percent of people
• Drowsiness -- up to 46 percent
• Weight gain -- up to 31 percent (see Clozapine and Weight Gain)
• Dizziness or vertigo (a spinning sensation) -- up to 27 percent
• Constipation -- up to 25 percent
• Insomnia -- up to 20 percent (see Clozapine and Insomnia)
• Nausea -- up to 17 percent
• Vomiting -- up to 17 percent
• Indigestion or heartburn -- up to 14 percent.

Some other common side effects (occurring in 1 to 7 percent of people) included:

• Headaches
• Shakiness (tremors)
• Increased sweating
• Dry mouth (see Clozapine and Dry Mouth)
• Nightmares
• Restlessness
• Agitation
• Confusion
• Fatigue or weakness
• Slurred speech
• Heartburn
• Diarrhea
• Loss of appetite
• Problems with bladder control
• Sexual problems (see Clozapine Sexual Side Effects)
• Vision changes
• Muscle weakness, spasms, or pain
• A sore throat
• Nasal congestion
• A sore or numb tongue.

Serious Side Effects
Some side effects with clozapine, while occurring infrequently, are potentially serious and should be reported to your healthcare provider. These include but are not limited to:

Signs of diabetes, such as:

• High blood sugar
• Increased thirst
• Frequent urination
• Extreme hunger (see Clozapine and Diabetes)

• Large or rapid weight gain
• Seizures
• Depression
• A rapid heart rate (tachycardia)
• Dizziness or fainting when going from a sitting or lying-down position to standing
• Feelings of internal restlessness or jitteriness
• Signs of an allergic reaction, including:

• An unexplained rash
• Hives
• Itching
• Unexplained swelling
• Wheezing
• Difficulty breathing or swallowing.
  

Clozapine can cause a dangerous side effect called agranulocytosis (dangerously low levels of white blood cells). In order to take the medication, you will be required to have regular blood tests to check for this side effect.

Rare Clozapine Side Effects
Rare clozapine side effects occur in less than 1 percent of people taking the drug. Because these side effects are so uncommon, it is difficult to tell whether they are caused by clozapine or something else.
These rare side effects include but are not limited to:

• Memory loss
• Water retention
• Stomach ulcers
• Vaginal itching
• Numbness
• Hot flashes
• A dry throat
• Joint pain
• A runny nose
• Wheezing
• Sneezing
• An increased appetite
• Bloodshot eyes.

Final Thoughts
You may experience some or none of the side effects listed in this article. Unfortunately, there is no way for your healthcare provider to know beforehand if you will have side effects from a medicine that you have never tried.

Therefore, make sure to let your healthcare provider know if you develop any side effects while taking the drug. You should also let your healthcare provider know if you develop something that "just does not seem right" during treatment. While it may not be a side effect of clozapine, your healthcare provider will be able to diagnose and treat the problem.source