Health and Wellness

Medical Marijuana Use and Mental Health

The potential medicinal properties of marijuana and its components have been the subject of research and debate for decades. THC has proven medical benefits in particular formulations. The U.S. Food and Drug Administration (FDA) has approved THC-based medications, dronabinol (Marinol®) and nabilone (Cesamet®), prescribed in pill form for the treatment of nausea in patients undergoing cancer chemotherapy and to stimulate appetite in patients with wasting syndrome due to AIDS.

When it comes to mental health conditions such as ADHD, anxiety, depression, and behavior-related illnesses, however, the evidence is far less clear. Because the potential benefits of THC for mental health remain uncertain, our clinic does not recommend its use in combination with psychiatric medications. THC can interfere with these prescriptions, reducing their effectiveness and potentially causing harmful effects to your health.

 

Long Term Effects

Little is known about the long-term impact of THC use by people with health, and/or age-related vulnerabilities—such as older adults or people with cancer, AIDS, cardiovascular disease, multiple sclerosis, or other neurodegenerative diseases. Further research will be needed to determine whether people whose health has been compromised by disease or its treatment (e.g., chemotherapy) are at greater risk for adverse health outcomes from marijuana use.

 

Side Effects

Possible side effects of medical marijuana may include:

  • Increased heart rate
  • Dizziness
  • Impaired concentration and memory
  • Slower reaction times
  • Negative drug-to-drug interactions
  • Impaired short-term memory
  • Increased risk of heart attack and stroke
  • Increased appetite
  • Potential for addiction
  • Cyclic vomiting syndrome
  • Hallucinations or mental illness
  • Withdrawal symptoms

THC and Mental Health: What the Latest Research Shows

ADHD

Research is very limited.

    • The only randomized controlled trial in adults (THC:CBD in a balanced spray) did not meet its main goal of reducing ADHD symptoms.

    • Some people report less restlessness, but memory and attention can worsen—especially with high-THC products.

    • Surveys suggest some reduce their ADHD medication while using cannabis, but these are self-reports and don’t prove benefit.
      References: Cooper et al., 2017; Francisco et al., 2023; Hernández et al., 2022; Hergenrather et al., 2020.

Anxiety

THC has a biphasic effect:

      • Low doses may feel calming for some people.

      • Higher doses often trigger anxiety, panic, or restlessness.

    • Long-term or heavy cannabis use is associated with higher odds of anxiety disorders in population studies.

    • CBD (a non-intoxicating cannabinoid) tends to have a more consistent calming effect and may reduce THC-induced anxiety.
      References: Turna & Lichenstein, 2024; Buckner & Hoch, 2024; Cooper et al., 2025.

Depression

  • Current studies do not support THC as an antidepressant.

  • Large reviews show cannabis use—especially frequent or high-THC use—is linked to more depressive symptoms, a higher likelihood of developing major depression, and worse outcomes in people already diagnosed.

  • These studies can’t always prove cause and effect, but the trend is consistently unfavorable for mood.
    References: Sorkhou et al., 2024; Churchill et al., 2025; Solmi et al., 2023. 

Key Takeaways

ADHD: No proven benefit; potential cognitive downsides.

Anxiety: Low doses may help short-term, but high doses often make symptoms worse.

Depression: No evidence THC treats depression; heavy/frequent use may worsen mood.

If cannabis is used, consider CBD-dominant products, avoid high-THC potency, and monitor for worsening mood, anxiety, or focus.