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Ketamine Seizures and Other Potential Side Effects and Dangers

As an infamous club drug, ketamine (often called Special K) is known for putting users in a trance-like state and providing them with an extreme out-of-body high.

Perhaps less widely known are the other extreme effects that ketamine, a potent dissociative anesthetic, can have on its users. The dangers can be long-lasting and even life threatening.

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The risk of severe side effects rises when considering that recreational ketamine is only available on the black market, where there are no regulations. Dosing is highly unpredictable, and the product may be cut with other street drugs like PCP or methamphetamine.

According to the Drug Abuse Warning Network, in 2011, there were 1,150 emergency room visits related to serious effects from illegal ketamine use.

Extreme Potential Side Effects of Ketamine


An extremely high dose of ketamine may put an individual into what’s known as a K-hole — a state on the verge of being completely subdued by ketamine as an anesthetic. This state of consciousness is highly unpredictable.

Some users report a pleasant experience, or they have no memory of it at all. Others describe their time in a K-hole as a terrifying near-death ordeal that left them traumatized.

When used as an anesthetic on humans in surgical procedures, ketamine is known to cause nightmares or delirium in users as they awaken from being subdued. It’s known as a “reemergence phenomenon” and may be related to the K-hole experience. In medical settings, this side effect may be lessened or avoided by administering a benzodiazepine.


Ketamine provides pain-blocking effects to users. This, combined with the perception-altering characteristics of the drug, can lead to individuals seriously injuring themselves and not even realizing it.


At high doses, ketamine can render a user almost completely subdued, unaware of their surroundings or what is happening in real time. Because of this, users can become highly vulnerable to sexual attacks. This is one reason ketamine is known as a date rape drug.  It’s odorless, and in powder or liquid form, it can easily be slipped into an unknowing individual’s drink.


Because of the limited research done on ketamine addiction and dependence, the long-term effects of ketamine use on the brain are largely unknown. However, users have reported long-lasting side effects of ketamine — including memory loss, impaired motor skills, and depression — that indicate the drug may cause lasting brain damage.

A 2013 report cites a study, conducted with magnetic resonance imaging, in which ketamine-caused lesions remained unchanged in users for 12 years after abstaining from the drug.


Ketamine is highly toxic to the bladder. It can cause severe damage to both the bladder and the urinary tract system. Long-term use may result in ketamine bladder syndrome, which can cause bladder swelling, incontinence, bladder ulcers, and blood in urine.

Ketamine can also thicken the bladder and urinary tract walls. In severe cases, these walls are too thick for urine to pass through, requiring long-term users to have their bladders removed. The kidneys and liver may also become compromised after long-term use of ketamine. They are damaged through repeated metabolization of the drug.


Ketamine was first synthesized as an alternative to PCP (phencyclidine), which caused seizures and other negative effects in patients when used as a general anesthetic. Still, research indicates that ketamine may have both proconvulsant and anticonvulsant properties.

In a 2002 study of eight epilepsy patients undergoing dental work under ketamine anesthesia, three had a seizure of some type. High doses of street-level ketamine have been reported to cause seizures in users as well, resulting in the need for emergency care and support. Individuals with any history of epilepsy may be more prone to ketamine-induced seizures.

Overdose: The Most Serious Risk

Because a user’s reaction to ketamine is so unpredictable and the dosing of street drugs is unregulated, users are at risk of an overdose every time they take the drug, particularly when taking a high dose. A high dose may be considered anything larger than 1 to 2 mg per kg (milligram per kilogram) of body weight. Street ketamine may be cut with other substances, such as PCP or methamphetamine (meth); therefore, these dosing parameters may not apply.

The effects of a ketamine overdose will vary greatly, depending on the dosage and the user’s physical makeup, including body mass and whether they have any pre-existing conditions, such as epilepsy, heart disorders, or central nervous system disorders.

Signs of a severe ketamine overdose may include vomiting, inability to speak or stand, unconsciousness, visual and auditory disturbances, hypothermia, and a slowed or depressed heart rate.

Extremely high doses of ketamine may cause a life-threatening or even fatal overdose. Signs that a user’s life may be in danger include seizures, loss of consciousness, and coma.

There is no antidote for a ketamine overdose. Users in emergency care for an adverse reaction to ketamine are provided with supportive care. Acute symptoms, like hypothermia or seizures, are treated. Breathing and oxygen assistance may be supplied if needed, and a user’s heart rate, blood pressure, and respiratory function will be monitored carefully.

There is limited information available on ketamine overdoses and related deaths. Many users who visit the emergency room experiencing adverse reactions are under the influence of other drugs as well, like MDMA (ecstasy) or prescription medications, which makes it harder for researchers to examine the statistics of ketamine-related deaths.

However, a 2014 study conducted by the National Poison Data System cited 327 reports of ketamine poisoning, one fatal (0.3 percent).

Because the dosing of street ketamine, and its interaction with a user’s unique physical and physiological makeup, is so unpredictable, a person could overdose during their first experience with the drug. Long-term users who have become dependent on the drug are also at high risk for overdose, as they have likely developed a tolerance to ketamine and may be using higher doses as a result.

No Safe Use

Ketamine use comes with the potential for very serious side effects, such as seizures, organ damage, accidents, and overdose. To ensure your safety, opt against any use of the drug.