Cannabis Side Effects: Short-Term and Long-Term

Cannabis side effects include dry mouth, red eyes, fast heart rate, dizziness, memory problems, and anxiety. Most effects start within minutes after smoking or vaping. Edibles take 30 to 120 minutes. High doses raise the risk of serious effects.

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Common short-term side effects

• Dry mouth
• Dry eyes
• Red eyes
• Increased heart rate
• Dizziness
• Impaired coordination
• Drowsiness
• Increased appetite
• Memory problems
• Anxiety or paranoia

These effects last 1 to 3 hours after inhalation. Edible effects last 4 to 8 hours or longer.

rare cannabis side effects

Side effects by method

Inhaled (smoking or vaping)

Effects start in seconds to minutes. Peak at 15 to 30 minutes. Last 1 to 3 hours. Smoking adds lung risks: cough, wheezing, bronchitis.

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Edibles and drinks

Effects start in 30 to 120 minutes. Peak at 2 to 4 hours. Last 4 to 8 hours. Overeating is common because effects are delayed. High doses cause vomiting and panic.

Tinctures and topicals

Tinctures under the tongue start in 15 to 45 minutes. Topicals cause few side effects. Some people get skin irritation.

Serious side effects

• Cannabinoid hyperemesis syndrome: repeated vomiting, stomach pain, hot showers for relief. This can last for days.
• Psychosis: hallucinations, delusions, confusion. Risk rises with high THC doses and daily use.
• Heart problems: chest pain, very fast heart rate, heart attack. Risk is higher in people with heart disease.
• Lung problems: chronic bronchitis, infections. Smoking cannabis harms lungs.

Long-term effects

• Cannabis use disorder: craving, withdrawal, inability to stop.
• Cognitive problems: attention, memory, learning.
• Respiratory problems: chronic cough, phlegm.
• Mental health: depression, anxiety, psychosis in some people.

Who is at higher risk

• Teens and young adults. Brain development continues to age 25.
• Pregnant people. THC can affect fetal development.
• People with heart disease or high blood pressure.
• People with a personal or family history of psychosis.
• Older adults. Falls and confusion are risks.

Drug interactions

Cannabis interacts with many medicines. Blood thinners: cannabis can raise bleeding risk. Benzodiazepines and opioids: cannabis adds sedation. Antidepressants and antipsychotics: cannabis can change drug levels. CBD can raise levels of some epilepsy drugs. Talk to a doctor or pharmacist.

Reduce risk

• Start with a low dose. Wait 2 hours before taking more.
• Do not drive or operate machines after use.
• Avoid alcohol and other drugs.
• Use products with known THC and CBD content.
• Store products away from children and pets.

When to get medical help

Call 911 or go to an emergency room for chest pain, severe vomiting, confusion, hallucinations, or trouble breathing. For non-emergency concerns, contact a doctor or poison control.