Almost half of people who regularly or heavily use marijuana go through withdrawal when they stop, according to a new study.

An analysis of 47 studies including more than 23,500 participants found about 47% of people who frequently use marijuana who seek treatment have “cannabis withdrawal syndrome” when they stop, HealthDay reports.

Marijuana withdrawal symptoms include nervousness, anxiety, sleeplessness, depression, restlessness and irritability, according to Dr. Timothy Brennan, Director of the Addiction Institute of Mount Sinai in New York City.

The results of the study suggest that withdrawal is likely or possible for a large majority of people who use marijuana, particularly those who heavily use the drug, said Emily Feinstein, Executive Vice President of the Center on Addiction, who was not involved in the study. “People should be prepared to experience withdrawal if they are going to stop using marijuana, and ideally consult a health care provider to help manage the symptoms and reduce the risk of relapse,” she said.