Foaming or frothing at the mouth occurs when excess saliva pools in the mouth or lungs and mixes with air. Causes include drug overdose, seizures, pulmonary edema, and rabies. It is usually a medical emergency.

Unintentional foaming is usually a sign of a serious medical condition that requires emergency medical care. It is essential to seek immediate medical help if a person begins foaming at the mouth.

Even if a small amount of bubbly saliva spills out of the mouth, a person may need emergency medical attention.

If someone starts to foam at the mouth, a bystander should roll them on their side, make sure their airways are clear, and call emergency services or take them to the nearest hospital.

Read on to learn more about what can cause foaming at the mouth. This article also looks at treatment options.

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There are numerous possible causes of foaming at the mouth.

Foaming at the mouth is normally associated with central nervous system problems with life threatening complications, including coma and death.

Drug overdose

When someone consumes more drugs or toxins than their body can process, they may experience an overdose.

A severe overdose may cause drooling or saliva to pool in the mouth and be pushed through clenched teeth and lips.

In particular, an opioid overdose can cause foaming at the mouth. A 2017 report found that foaming at the mouth was a possible, though uncommon, characteristic of fentanyl overdose.

Other symptoms of opioid overdose can include:

  • the body going limp
  • pale face or skin that is clammy to the touch
  • blue or purple color to the nails
  • vomiting
  • making gurgling noises
  • slow heart rate
  • slow breathing or inability to breathe
  • inability to speak
  • loss of consciousness

Learn more about recognizing the signs of an opioid overdose.

Pulmonary edema

People with severe overdoses may also experience a heart attack, which can cause pulmonary edema. This is where fluid leaks into the lungs due to pressure.

This can cause frothing from the mouth. It may be pink-tinted, and happens as a result of a person struggling to breathe.

Other causes of pulmonary edema include:


People with seizure disorders or epilepsy can experience a few different types of seizures, each with its own unique set of symptoms.

Usually, only one type of seizure, which is called a tonic-clonic seizure, causes drooling, slight foaming, or bubbling at the mouth.

People experiencing tonic-clonic seizures have abnormal electrical firing throughout the brain simultaneously. It can cause a loss of muscle control, which can make it difficult to swallow or open the mouth.

During a seizure, this excess salvia tends to pool in the mouth before being thrust through clenched teeth, mixing with oxygen and gases in the mouth, and developing a foamy appearance.

Tonic-clonic seizures usually cause an immediate loss of consciousness followed by whole-body convulsions.


The rabies virus is a zoonotic disease, meaning it can cross over from animals to humans.

One of the symptoms of rabies is paralysis of the throat muscles, which makes it difficult to swallow.

Rabies also causes saliva production to increase. Saliva may then pool in the mouth and mix with oxygen and other gases when a person is unable to swallow.

Initial symptoms of rabies last for a number of days, and can include:

  • fever
  • weakness
  • headache
  • tingling or burning sensation at the site of the wound

Other symptoms can include:

Rabies can infect and damage the brain and central nervous system of all types of warm-blooded mammals. The virus transmits from one host to the next through the saliva of an animal with rabies.

Anyone who is foaming at the mouth or sees someone who is should seek emergency medical attention immediately.

Treatment will vary depending on the cause of foaming at the mouth, but emergency treatment is usually necessary to prevent serious, irreversible complications.

Drug overdose

Anyone experiencing a drug overdose should be admitted to a hospital as soon as possible, and have continuous medical monitoring to prevent serious health risks, such as organ failure, coma, and death.

It can take only 1–3 hours from the time of the overdose to cause death.

If someone is or may be experiencing an overdose, a witness should call emergency services or drive them to the nearest hospital.

While waiting for help to arrive, a person should roll the individual over onto their side and make sure their airways are clear. It is important to not leave anyone experiencing an overdose on their own.

People who overdose on ingestible toxins, such as alcohol or liquid chemicals, may require a stomach pump or activated charcoal to remove the toxin.

If the overdose was caused by an opioid, a person may receive an injection of an opioid overdose reversal medication (OORM), such as naloxone, to immediately reverse the action of the drug. However, naloxone will not work on overdoses caused by stimulant drugs.

If a person experiences a heart attack or pulmonary edema due to a drug overdose, they may require separate treatments for the complications.

Pulmonary edema

Quick treatment is essential for pulmonary edema. It is important to seek immediate medical help as soon as a person has concerns about pulmonary edema.

Treatments they may receive include:


A person having a seizure will require first aid at the time of the seizure. Medical treatment may also be necessary.

First aid

If someone is experiencing a seizure, a bystander should:

  • make sure they are at a safe distance from anything that could harm them.
  • use blankets or towels to form padding between the person and any nearby wall
  • remove any furniture surrounding them, such as chairs, tables, or electrical appliances
  • never try to place anything in the mouth of someone having a seizure
  • stay with a person who is having a seizure until it is over
  • time how long the seizure lasts

Once the convulsions stop and someone starts to regain consciousness, the bystander can roll the individual onto their side. It is essential to make sure their mouth and nose are clear.

Learn about what a person can do if they feel they are about to have a seizure.

Medical treatments

People who have epilepsy may not need to seek emergency care every time they have a seizure. However, a person should seek immediate medical help if:

  • the seizure lasts for more than 5 minutes
  • this is the person’s first seizure
  • the person has multiple seizures in a row
  • the person experiences a serious injury
  • the person has difficulty breathing after the seizure

If it is someone’s first seizure or the seizure is different than usual, doctors will do tests to determine the underlying cause.

Some people with seizure disorders and types of epilepsy require lifelong management medications called anti-seizure or anticonvulsive drugs.

Learn more about medications for seizures.


Anyone who thinks they may have been exposed to the rabies virus should contact a medical professional straight away.

Recommendations for people who may have encountered the rabies virus include:

  • vigorously washing the wound with soap under a running tap, then continuing to flush the area with water for 15 minutes
  • applying antiviral or iodine-containing medication to the area 15 minutes after washing
  • avoiding covering the wound with a bandage or dressing

Go to a hospital, local health clinic, or a doctor for post-exposure prophylaxis shots as soon as possible. These vaccines can prevent the virus from forming an infection.

Here are some frequently asked questions about foaming at the mouth.

What drug causes foaming at the mouth?

Opioid overdose, such as from fentanyl, can cause foaming at the mouth. It is essential to seek immediate medical help if they experience foaming at the mouth or other signs or symptoms of a drug overdose.

What virus causes foaming at the mouth

Rabies is a viral infection that can cause foaming at the mouth in humans and animals. It transmits from animals to humans through saliva, such as through a dog bite.

Can foaming at the mouth indicate a heart attack?

A heart attack can increase pressure within the heart, which can result in pulmonary edema, or a buildup of fluid in the lungs. Pulmonary edema can cause a person to produce thick, pink-tinted foam at the mouth.

What causes foaming at the mouth while sleeping?

A person may experience hypersalivation, or excessive drooling, while they sleep. However, if the saliva is foaming, it may indicate a serious condition such as rabies or seizures.

If a person experiences foaming at the mouth at night, it is important to seek immediate medical help for an accurate diagnosis.

Possible causes of foaming or frothing at the mouth include drug overdose, tonic-clonic seizures, and rabies.

If a person suspects a drug overdose, it is essential to seek immediate medical help. A person should also seek medical advice if they suspect exposure to rabies.

Tonic-clonic seizures do not always require medical attention. However, a person should contact emergency services if it is the person’s first seizure, they experience multiple seizures, or they have a serious injury.