context: If you're like most folks, you probably think hallucinations have to do with seeing things that aren't really there. But there's a lot more to it than that. It could mean you touch or even smell something that doesn't exist. There are many different causes. It could be a mental illness called schizophrenia, a nervous system problem like Parkinson's disease, epilepsy, or of a number of other things. If you or a loved one has hallucinations, go see a doctor. You can get treatments that help control them, but a lot depends on what's behind the trouble. There are a few different types. Hallucinations most often result from: Schizophrenia. More than 70% of people with this illness get visual hallucinations, and 60%-90% hear voices. But some may also smell and taste things that aren't there. Parkinson's disease. Up to half of people who have this condition sometimes see things that aren't there. Alzheimer's disease. and other forms of dementia, especially Lewy body dementia. They cause changes in the brain that can bring on hallucinations. It may be more likely to happen when your disease is advanced. Migraines. About a third of people with this kind of headache also have an "aura," a type of visual hallucination. It can look like a multicolored crescent of light. Brain tumor. Depending on where it is, it can cause different types of hallucinations. If it's in an area that has to do with vision, you may see things that aren't real. You might also see spots or shapes of light. Tumors in some parts of the brain can cause hallucinations of smell and taste. Charles Bonnet syndrome. This condition causes people with vision problems like macular degeneration, glaucoma, or cataracts to see things. At first, you may not realize it's a hallucination, but eventually, you figure out that what you're seeing isn't real. Epilepsy. The seizures that go along with this disorder can make you more likely to have hallucinations. The type you get depends on which part of your brain the seizure affects. You may sense that the sounds are coming from inside or outside your mind. You might hear the voices talking to each other or feel like they're telling you to do something. Causes could include: Schizophrenia Bipolar disorder Psychosis Borderline personality disorder Posttraumatic stress disorder Hearing loss Sleep disorders Brain lesions Drug use For example, you might: See things others don't, like insects crawling on your hand or on the face of someone you know See objects with the wrong shape or see things moving in ways they usually don't Sometimes they look like flashes of light. A rare type of seizure called "occipital" may cause you to see brightly colored spots or shapes. Other causes include: Irritation in the visual cortex, the part of your brain that helps you see Damage to brain tissue (the doctor will call this lesions) Schizophrenia Schizoaffective disorder Depression Bipolar disorder Delirium (from infections, drug use and withdrawal, or body and brain problems) Dementia Parkinson's disease Seizures Migraines Brain lesions and tumors Sleep problems Drugs that make you hallucinate Metabolism problems Creutzfeldt- Jakob disease You may think the odor is coming from something around you, or that it's coming from your own body. Causes can include: Head injury Cold Temporal lobe seizure Inflamed sinuses Brain tumors Parkinson's disease You may feel that something you eat or drink has an odd taste. Causes can include: Temporal lobe disease Brain lesions Sinus diseases Epilepsy You might think you're being tickled even when no one else is around, or you may feel like insects are crawling on or under your skin. You could feel a blast of hot air on your face that isn't real. Causes include: Schizophrenia Schizoaffective disorder Drugs that make you hallucinate Delirium tremens Alcohol Alzheimer's disease Lewy body dementia Parkinson's disease First, your doctor needs to find out what's causing your hallucinations. He'll ask about your medical history and do a physical exam. Then he'll ask about your symptoms. He may need to do tests to help figure out the problem. For instance, an EEG, or electroencephalogram, checks for unusual patterns of electrical activity in your brain. It could show if your hallucinations are due to seizures. You might get an MRI, or magnetic resonance imaging, which uses powerful magnets and radio waves to make pictures of the inside of your body. It can find out if a brain tumor or something else, like an area that's had a small stroke, could be to blame. Your doctor will treat the condition that's causing the hallucinations. This can include things like: Medication for schizophrenia or dementias like Alzheimer's disease Antiseizure drugs to treat epilepsy Treatment for macular degeneration, glaucoma, and cataracts Surgery or radiation to treat tumors Drugs called triptans, beta-blockers, or anticonvulsants for people with migraines Your doctor may prescribe pimavanserin ( Nuplazid). This medicine treats hallucinations and delusions linked to psychosis that affect some people with Parkinson's disease. Sessions with a therapist can also help. For example, cognitive behavioral therapy, which focuses on changes in thinking and behavior, helps some people manage their symptoms better.