What causes a human to foam around the mouth?

There are several possible causes of foaming at the mouth in humans. Some of the most common include:

- Seizures: Foaming at the mouth is a common symptom of epileptic seizures, especially generalized tonic-clonic seizures (formerly known as grand mal seizures). These seizures cause a loss of consciousness and violent muscle contractions, which can lead to air being forced out of the lungs and saliva being produced in excess.

- Rabies: Foaming at the mouth is a classic symptom of rabies, a fatal viral infection of the central nervous system. The virus causes inflammation of the brain and spinal cord, leading to a range of symptoms including aggression, agitation, difficulty swallowing, and excessive salivation.

- Head injury: A severe head injury can cause damage to the brain, leading to seizures, loss of consciousness, and foaming at the mouth.

- Drug overdose: An overdose of certain drugs, such as opioids or stimulants, can cause foaming at the mouth. This is because these drugs can depress the central nervous system, leading to a loss of consciousness and decreased muscle tone, which can allow saliva to pool in the mouth and be expelled as foam.

- Mental illness: Foaming at the mouth can sometimes be a symptom of a mental illness, such as schizophrenia or psychosis. These conditions can cause delusions, hallucinations, and disorganized behavior, which can lead to excessive salivation and foaming at the mouth.

- Poisoning: Ingestion of certain poisons, such as strychnine or cyanide, can cause foaming at the mouth. These poisons affect the nervous system, leading to seizures, muscle spasms, and excessive salivation.