Short-term side effects of ketamine use may include headache, dizziness, sleepiness, feeling strange or “loopy,” difficulty speaking, numbness, blurred vision, or nausea. Ketamine may also cause changes in blood pressure and heart rate.11

Studies show that unsupervised ketamine use may have serious health risks.1 These include respiratory depression, which is dangerously slow and shallow breathing. A NIDA-funded study found that problems related to ketamine use reported to poison control centers increased 81% from 2019-2021. The use of other drugs along with ketamine, especially opioids or GHB, another club drug, led to the most health problems, some of them life-threatening.12

Long-term, heavy ketamine use is associated with memory problems, depression, and anxiety.13 At high doses, ketamine may cause psychosis, a mental illness that causes a person to lose touch with reality. Frequent recreational ketamine use can lead to delusions that can last to up to one month after a person stops using it.14

Long-term use of ketamine may cause gastrointestinal problems, including abdominal pain sometimes called k-cramps5. Ketamine use can also cause ketamine-induced uropathy, a treatable but potentially serious condition that causes symptoms like those of a urinary tract infection.15,16

From NIDA.