Short Answer
Marijuana's most common side effects are short lived and include dry mouth, red eyes, impaired coordination, slower reaction time, short term memory trouble, drowsiness, and changes in mood. Anxiety, paranoia, and a racing heartbeat are less common but more likely with high THC doses, with edibles, and for people who are new to cannabis. Most effects fade within a few hours. Edible effects can last six hours or longer.
What Are the Long-Term Side Effects of Weed?
Common Short Term Side Effects
These are the effects reported most often after smoking, vaping, or eating cannabis.
How Long Do Cannabis Side Effects Last? A Guide to THC and CBD Duration
- Dry mouth and increased thirst.
- Bloodshot, dry, or itchy eyes.
- Slower reaction time and clumsiness.
- Short term memory lapses and trouble following a conversation.
- Sleepiness or a heavy, relaxed feeling.
- Fast heartbeat, sometimes with dizziness on standing.
- Anxiety, unease, or paranoia.
- Increased appetite.
- Nausea or, with high doses, vomiting.
- Headache or lightheadedness.
Side Effects by Method
Smoking and Vaping
- Coughing, wheezing, and throat irritation.
- Effects begin within minutes and peak fast.
- Frequent smoking is linked to bronchitis and airway irritation.
Edibles and Drinks
- Delayed onset, often 30 to 120 minutes.
- Stronger peaks and longer duration, which makes overconsumption easier.
- Higher rates of nausea, vomiting, panic, and rapid heartbeat.
Tinctures, Oils, and Topicals
- Sublingual oils act faster than edibles and slower than smoke.
- Topicals rarely cause anything beyond local skin irritation.
- Drowsiness and dry mouth are the usual complaints with ingested oils.
Effects That Need Medical Attention
Get help if you notice any of these after using marijuana.
- Chest pain, pressure, or a heartbeat that will not settle.
- Severe confusion, hallucinations, or a panic attack you cannot calm down.
- Repeated vomiting, especially with stomach pain or hot showers to find relief.
- Fainting, seizure, or trouble breathing.
- Signs of a psychotic episode, such as hearing voices or losing touch with reality.
Who Faces Higher Risk
- People under 25, whose brains are still developing.
- Anyone with a personal or family history of psychosis, schizophrenia, or bipolar disorder.
- People with heart conditions or high blood pressure.
- Pregnant or breastfeeding people.
- Anyone taking sedatives, blood thinners, or drugs that affect the liver.
- New users and people who take a large dose by mistake.
Regular, heavy use is linked to cannabis use disorder, persistent memory problems, and worsening anxiety or depression in people who are already vulnerable. These risks grow with frequency and potency.
How to Lower Your Risk
- Start with a low dose, especially with edibles, and wait at least two hours before taking more.
- Pick products with a clear THC and CBD content so you know what you are getting.
- Choose lower THC options if you are new or sensitive to anxiety.
- Avoid mixing cannabis with alcohol or sedatives.
- Do not drive or operate machinery until effects pass.
- Keep a note of how each product affects you.
What About CBD Products
CBD products carry their own side effects, though they tend to be milder. Reported issues include drowsiness, dry mouth, diarrhea, reduced appetite, and changes in liver enzymes. CBD can interact with prescription drugs because it affects some of the same liver enzymes, so check with a pharmacist if you take medication. Full spectrum products may contain small amounts of THC, which can show up on a drug test and cause mild psychoactive effects in sensitive people. Third party lab testing is the best way to confirm what a bottle actually contains.