Psychosis arises as part of another mental health condition. Psychosis is categorized into three main groups, based on the cause of the condition and these include:

• Psychosis resulting from a mental or psychological condition
• Psychosis resulting from a general medical health condition
• Psychosis resulting from drug abuse or alcohol misuse

Psychosis due to mental disorders

Psychosis is a feature of certain mental illnesses, examples of which include:

Schizophrenia
This is a long term disorder that is typically characterized by hallucinations and delusions.

Bipolar disorder 
This is a mood disorder, characterized by a mood that swings between depressive and manic. It is also called manic depressive psychosis.

Major depressive disorder can cause psychosis.

Severe stress, anxiety disorder, panic disorder, dementia, or insomnia may also result in psychosis

Psychosis due to medical disorders

Psychosis may be seen in several debilitating medical conditions such as:

• Infections - Certain infections with bacteria, viruses and parasites such as HIV and AIDS, syphilis, malaria and Lyme's disease.
• Parkinson's disease - A drug used to treat Parkinson's disease cam cause symptoms of psychosis
• Alzheimer's disease
• Multiple sclerosis
• Abnormally low levels of blood sugar or hypoglycemia
• Autoimmune disorders
• Brain tumours
• Electrolyte disorders such as low or high levels of calcium, sodium, potassium, magnesium or phosphates

Psychosis due to drug and substance abuse

Drug abuse and alcoholism may also lead to psychosis and examples of substances that can induce the condition include:

• Binge drinking
• Alcohol withdrawal in alcoholics
• Cocaine
• Amphetamine or methamphetamine
• Ecstasy or MDMA
• Mephedrone or MCAT
• LSD
• Cannabis
• Ketamine
• Magic mushrooms or psilocybins