Cannabis Side Effects: The Honest Guide You Deserve (2026)

THC inhibits saliva production by acting on cannabinoid receptors in the salivary glands. Stay hydrated, suck on hard candy, or chew gum. Avoid alcohol, which makes it worse.

Manage: Drink water, avoid alcohol

THC causes blood vessels to dilate, including in the eyes. This is actually related to its blood pressure-lowering effect. Eye drops provide immediate relief.

Manage: Use lubricating eye drops

THC activates hunger signals in the hypothalamus and enhances the reward response to food flavors and aromas. Can be a benefit (appetite stimulation for medical patients) or an annoyance.

Manage: Prepare healthy snacks beforehand

THC disrupts hippocampal function, making it harder to form new memories during intoxication. This is temporary and resolves as THC clears. Does not affect long-term memory formation.

Manage: Write things down, avoid important tasks

THC impairs motor coordination and reaction time. This is why you should never drive under the influence. Effects last 2-4 hours for inhaled cannabis.

Manage: Never drive. Plan activities beforehand.

Heart rate increases 20-50% within minutes and lasts 1-3 hours. Usually harmless for healthy adults but can feel unsettling, especially combined with anxiety.

Manage: Sit down, breathe slowly, stay calm

Can occur from blood pressure changes, especially when standing up quickly (orthostatic hypotension). More common with first-time use or high doses.

Manage: Sit or lie down, stay hydrated

Anxiety and paranoia

Low THC doses tend to reduce anxiety. High doses can trigger intense anxiety, paranoia, and panic attacks. This is the most common cause of emergency room visits related to cannabis. If this happens, it will pass. Find a calm space, breathe slowly, and wait.

Threshold: Usually 15mg+ THC for sensitive individuals

Nausea and vomiting

Paradoxically, while cannabis treats nausea at moderate doses, very high doses or chronic heavy use can cause cannabinoid hyperemesis syndrome (CHS), characterized by cyclic severe nausea and vomiting. Hot showers provide temporary CHS relief.

Threshold: Very high doses or chronic heavy daily use

Severe disorientation

At very high doses, particularly from edibles, people can experience profound confusion, depersonalization, or dissociation. This is frightening but temporary. It usually resolves within 2-6 hours.

Threshold: Usually 50mg+ THC, especially in edibles

Psychotic-like symptoms

Very high THC doses can temporarily produce psychotic-like symptoms including hallucinations, delusions, and severe paranoia. These resolve as THC clears but are extremely unpleasant. More likely in people with genetic vulnerability.

Threshold: High doses, especially in predisposed individuals

Anxiety disorders

CBD may help. High-THC products carry significant risk. See our cannabis and anxiety guide.

Depression

Complex relationship. Some find relief, others find worsened symptoms with heavy use. Monitoring is important.

Psychosis/schizophrenia risk

The strongest contraindication. People with family history of psychotic disorders should exercise extreme caution with high-THC cannabis.

PTSD

Growing evidence that cannabis may help, particularly with nightmares and hyperarousal. Research is active.

Bipolar disorder

Cannabis may trigger manic episodes in some individuals with bipolar disorder. Discuss with your psychiatrist.