Medication resource centre

Table of Contents




Common Side Effects with Antipsychotics

Movement Disorders

Other Potential Side Effects 

Managing Side Effects



Side effects are the body’s reaction (emotional or physical or both) to a medication. Lists of side effects can sound or look alarming. It is a good idea to be prepared by reading about the potential side effects before starting treatment. Individuals will experience side effects differently. Some individuals may experience many side effects, while others may experience very few or none. For some individuals, side effects can be very troubling and may impact adherence to the medication. For others side effects may be very mild and cause no concerns.
Although antipsychotics have many common side effects, some medications may be less likely than others to cause the different side effects listed in this section. Side effects with each medication are different. Just because you experience side effects with one medication does not mean you will experience side effects with another medication.  
It is also important to know that many of the side effects that occur with antipsychotic medications can be treated. Some side effects are related to the dose (dose-related side effects), hence sometimes decreasing a dose even slightly can improve side effects. Some side effects commonly occur at the beginning of treatment and with dose increases but improve as you stay on the medication longer. Finally, there are often other medications or non-medication strategies that can be used to manage side effects if necessary.  
If you are experiencing side effects, tell your doctor and pharmacist. They can suggest ways to help you manage the side effects.  
The side effect lists stated for individual antipsychotic medications in this online resource are not comprehensive. They contain some of the most common side effects that individuals may experience as well as some very rare side effects that can be very serious if individuals experience them. Discuss with your doctor and pharmacist the full range of side effects that may occur with your prescribed medication.

Common Side Effects with Antipsychotics[1]
Movement Disorders

Because antipsychotic medications interfere with the neurotransmitter dopamine, which is important in controlling movement, many of the side effects involve movement. These are called extrapyramidal symptoms. They can include: movement changes similar to Parkinson’s disease (Parkinsonism), loss of movement (akinesia), restlessness (akathisia), and muscle spasms (dystonia). The typical antipsychotics are associated with more movement-related side effects compared to atypical antipsychotics, however, they can occur with both groups. Clozapine is the only antipsychotic thought to NOT cause movement-related side effects in individuals.
Long-term use of antipsychotic medication can cause permanent extrapyramidal symptoms even after the medication is stopped. This is called tardive dyskinesia.[2] This most commonly occurs with typical antipsychotic medications.


Some side effects resemble Parkinson's disease, which is caused by the loss of dopamine. This can make muscles stiff and weak, reduce the animation in the face, cause the hands to shake, and make fine movement difficult.

Loss of Movement (akinesia)

Akinesia or bradykinesia are terms used to describe a slowing of movement that individuals may experience while taking antipsychotic medications. Individuals may lose the ability to move easily and quickly due to blocking of dopamine receptors in the movement area of the brain.

Restlessness (akathisia)

A person on antipsychotic medication may feel intensely restless and unable to sit still. This is more than just a physical restlessness and can result in a feeling of being tense and uneasy. If you experience feelings of inner or outer restlessness it is important to notify your doctor. This is a dose-related side effect and often a small decrease in the dose of the antipsychotic can help you feel much better.

Muscle Spasms/Dystonia (dysphonia and oculogyric crisis)

These are acute muscle contractions that are uncontrolled and may be painful. This side effect most commonly occurs in the neck or shoulder. Sometimes the problem affects the muscles of the larynx (voice box), which makes it difficult to speak normally (dysphonia).
Another form of muscle spasm affects the muscles that control eye movements. This is called oculogyric crisis. This side effect makes the eyes turn suddenly. This is very unpleasant and can make a number of activities quite dangerous, for example, when pouring hot water or crossing a road.

Tardive Dyskinesia

Usually, tardive dyskinesia does not occur until after many months, if not years, of taking antipsychotic medications. Random movements—usually starting in the face and mouth as involuntary tongue movements and slight grimacing—most often characterize this side effect. The problem can spread to the rest of the body, with writhing movements in the limbs, muscle spasms, tremors and tics. The movements usually disappear during sleep.

Other Potential Side Effects

Some people may also experience drowsiness, especially when first starting the medication. Driving or operating machinery should be avoided until the medication effects are known. Drowsiness is often a side effect that people get used to over time. Also, taking the medications in the evening can help with management of this side effect.

Sexual Side Effects

After the use of some antipsychotics, some people may develop high levels of prolactin. Prolactin is a hormone that is involved in monthly menstrual cycle regulation, sexual desire and functions and breastmilk production after childbirth. The production of this hormone involves dopamine. Therefore, antipsychotic medications can increase the production of prolactin because of their effect on dopamine in the brain. This side effect is most significant with the typical antipsychotics. If you have high prolactin from your medication you may find you are not interested in having sex, you may experience premature ejaculation if you are a male and loss of menstrual periods if you are a female. Both males and females may experience swelling of the breasts and milk production. Over time, this high level of prolactin may lead to hormone imbalances which can also put both men and women at an increased risk of breaking a bone due to osteoporosis.

Heart Rate and Rhythm

Many antipsychotics can affect the heart’s rate and rhythm—especially at high doses. Antipsychotic medications can increase the risk of arrhythmias in certain individuals. Whatever the dose of your medication, unexplained blackouts or a sudden shortness of breath should be mentioned to your doctor. He or she may order a heart-tracing or a heart-rhythm monitor to be worn for a day or two to determine what is happening with your heart.

Eye Problems

Various antipsychotics may be responsible for different eye disorders. These can include blurred vision, difficulty reading and glaucoma (increased pressure inside the eye). If you experience any changes in vision or pain in your eyes during treatment with antipsychotic medications, discuss this with your doctor.

Metabolic Changes (e.g., weight gain, diabetes, dyslipidemia)

Antipsychotics have been associated with weight gain, diabetes and changes in cholesterol levels (dyslipidemia). Before starting antipsychotics, your doctor will consider whether these risks outweigh the benefits of treatment for you.  
After starting antipsychotics, you and your doctor should track your weight and your waist circumference. Other tests such as fasting blood glucose, lipid levels and blood pressure may also be done regularly. You might need to change medications if you gain weight quickly, become pre-diabetic or diabetic, or develop high blood pressure or dyslipidemia.[3] Many individuals who gain weight from antipsychotic medication can successfully lose the weight with support from healthcare providers.
Not all antipsychotic medication is equal when it comes to weight gain. Some medication causes more weight gain than others. Discuss with your doctor which medication is the best for you given your current weight and health status.

White Blood Cell Count

Antipsychotic medications can cause decreases in white blood cell counts. This side effect occurs most commonly with the atypical antipsychotics. This side effect is potentially concerning as people with low white blood cell counts are at a higher risk of serious infections. The overall risk of this side effect is very low. The medication that we are most concerned with is Clozapine. The risk of this side effect with Clozapine is approximately 1%.
For this reason, individuals who take Clozapine must have their white blood cell count monitored to ensure it does not drop too low. Individuals will have their blood monitored once per week for the first 6 months of treatment; every 2 weeks for the next 6 months of treatment; followed by every 4 weeks for the duration of treatment. The risk of this side effect with Clozapine is very low, however, the blood monitoring ensures patient safety by identifying when a drop occurs.
The drop in white blood cell count usually occurs within the first few months of treatment but can occur at any time. This is not a dose-related side effect therefore lowering the dose and treating with lower doses does not change the risk.
If you are taking Clozapine, discuss this side effect with your doctor.

Risk of Death in Older Adults with Dementia

Antipsychotic medications are commonly used to treat schizophrenia and other psychotic illnesses in older individuals. Older adults with dementia may have an increased risk of death while taking antipsychotics. The risk was originally identified for the atypical antipsychotics. However, the precaution/warning has been extended to all antipsychotic medication in Canada. Individuals with dementia who receive antipsychotic medication to help with behaviour symptoms have an increased chance of dying from infection or stroke. The risk seems to increase with higher doses.[4] In many cases the benefit of these medications may outweigh these risks. It is important to understand the risks and benefits of these medications in individuals with dementia. Discuss all potential risks of these medications with your doctor.

Managing Side Effects

Not everyone will have the same reaction to antipsychotic medications, so it is important to keep track of the effects the medication is having on you. Share this list with your doctor and pharmacist so they can help you manage your side effects effectively. Depending on the type and severity of your side effects, your doctor and pharmacist will have an approach that meets your individual needs.
Your pharmacist can provide a list of your prescribed medications, which should be kept in a safe place, in case you need access to this information during an emergency. Give a copy to a family member or a friend. Your doctor’s after-hours emergency telephone number should also be kept handy.


[1] Rummel-Kluge, C., Komossa, K., Schwartz, S., Hunger, H., Schmid, F., Kissling., W., et al. (2010). Second-generation antipsychotic drugs and extrapyramidal side effects: A systematic review and meta-analysis of head-to-head comparisons. Schizophrenia Bulletin, published online doi:10.1093/schbul/sbq042

Correll, C. U., Manu, P., Olshanskiy, V., Napolitano, B., Kane, J. M., Malhotra, A. K. et al. (2009). Cardiometabolic risk of second-generation antipsychotic medications during first-time use in children and adolescents. JAMA, 302(16), 1765-1773.

Lieberman, J. A., Stroup, T. S., McEvoy, J. P., Swartz, M. S., Rosenheck, R. A., Perkins, D. O., et al. (2005). Effectiveness of antipsychotic drugs in patients with chronic schizophrenia. The New England Journal of Medicine, 353(12), 1209-1223.

[2] Leucht S., Corves C., Arbter D., Engel R., Li C., & Davis, J. (2009). Second-generation versus first-generation antipsychotic drugs for schizophrenia: A meta-analysis. Lancet, 373(9657), 31-41. doi:10.1016/S0140-6736(08)61764-X

[3] [Consensus Development Conference on Antipsychotic Drugs and Obesity and Diabetes]

[4] Huybrechts, K., Gerhard, T., Crystal, S., Olfson, M., Avorn, J., Lucas, J., & Schneeweiss, S. (2012). Differential risk of death in older residents in nursing homes prescribed specific antipsychotic drugs: Population based cohort study. BMJ, 344, e977. doi: 10.1136/bmj.e977