• The effect marijuana has on the body is a good reason to prohibit its use in the workplace.
• The way marijuana is ingested impacts its effects and the length of impairment.

Marijuana has been legalized for medical and recreational use in many states, although it remains illegal under federal law. In May 2024, the Drug Enforcement Administration (DEA) proposed rescheduling marijuana from Schedule I to Schedule III of the Controlled Substances Act (CSA). Moving marijuana to this classification would legalize it for medical use nationwide. However, the proposal has not been finalized.

When determining how to address marijuana in the workplace, a company should take employee job duties, applicable state and federal regulations, and workplace culture into account. In all states, an employer can prohibit marijuana use in the workplace and prohibit all employees from being impaired by the drug. Just as a company doesn’t want employees to be impaired by alcohol while at work, it doesn’t want employees to be impaired by marijuana.

The short-term effects of marijuana use are a concern with regard to workplace safety. The chemical THC in marijuana acts on the parts of the brain that deal with memory, decision making, attention, and reaction time. Because of this, marijuana use can bring:

• Problems with problem-solving,
• Inattentiveness,
• Distorted perception,
• Slower reaction time,
• Impaired risk assessment,
• Impaired coordination, memory, and judgment.

Over-intoxication from marijuana can bring feelings of panic and paranoia, and studies have shown that some products may bring schizophrenia and psychotic disorders. In addition, cannabis can make the heart beat faster and raise blood pressure, increasing the risk for a heart attack or stroke.

How long after using is a person impaired by marijuana?

People react to marijuana differently. A person is going to be impaired for a few hours to a day or more after using marijuana, and the degree of impairment at a given point in time depends on several factors. How long a person will be negatively impacted by marijuana use will vary, depending on:

• How marijuana was ingested,
• A person’s body composition,
• A person’s tolerance to the drug.

Ingestion: Marijuana can be smoked, mixed into food or drinks, or vaped. When cannabis is consumed in an edible, intoxication is not going to occur right away, and the effects are going to last longer.

Body composition: The way a person is built, their age, and other biological and genetic factors make a difference in how quickly marijuana is metabolized.

Tolerance: A person who uses marijuana more often is going to have a higher tolerance.