Cannabis side effects include dry mouth, red eyes, a faster heartbeat, short-term memory trouble, anxiety, and poor coordination. How strong they get depends on the THC dose, the method of use, and your tolerance. Most reactions fade within a few hours, but high doses can trigger panic, vomiting, or chest pain that needs medical care.
What Are the Long-Term Side Effects of Weed?
What are the most common cannabis side effects?
Most short-term effects come from THC, the compound that causes the high. CBD, the compound sold in most CBD shops, does not cause a high and has a shorter list of side effects.
- Dry mouth and thirst
- Red or bloodshot eyes
- Faster heart rate, sometimes with palpitations
- Dizziness or lightheadedness
- Slower reaction time and poor balance
- Short-term memory lapses and trouble focusing
- Anxiety, paranoia, or panic, most often at high doses
- Drowsiness, or in some people restlessness
- Increased appetite
- Nausea or vomiting, more common with edibles
Why does THC cause these effects?
THC binds to CB1 receptors in the brain and nervous system. Those receptors help control mood, memory, appetite, pain signaling, and movement. When THC switches them on, the systems that handle those jobs slow down or misfire, which is what produces the high and the side effects at the same time.
CBD works through other paths. It does not activate CB1 receptors in a strong way, so it does not cause intoxication. CBD can still bring drowsiness, stomach upset, and changes in how the body breaks down some prescription drugs.
What Are the Common Side Effects of Marijuana?
How do THC and CBD side effects compare?
| Effect | THC | CBD |
|---|---|---|
| High or intoxication | Yes | No |
| Dry mouth, red eyes | Common | Rare |
| Anxiety or paranoia | Common at high doses | Uncommon at normal doses |
| Memory and focus problems | Yes, while high | Not linked |
| Drowsiness | Yes | Possible |
| Drug interactions | Yes | Yes, with certain medications |
Neither compound is free of risk. The difference is in the type and the odds, not in a clean split between safe and unsafe.
Do side effects change with how you use cannabis?
Yes. The route of use changes how fast effects start, how strong they feel, and how long they last.
Smoking and vaping
Effects start within seconds to a few minutes and peak in about 30 minutes. Smoke irritates the airways and can cause coughing, wheezing, and a sore throat. Vaping skips tar but still heats chemicals that can harm the lungs, so it is not a risk-free swap.
Edibles and drinks
Effects take 30 minutes to 2 hours to start because the THC passes through the liver first. The liver turns THC into 11-hydroxy-THC, a compound that hits harder and lasts longer. Bad reactions from edibles are a common reason people end up in the emergency room.
Tinctures, oils, and topicals
CBD tinctures held under the tongue start working in 15 to 30 minutes. Topical creams act only where you rub them, so they cause few whole-body effects. If you buy CBD, pick products with third-party lab tests so you know the exact THC level and can avoid an unexpected high.
How long do cannabis side effects last?
Inhaled THC effects last 1 to 3 hours. Edible effects can run 4 to 8 hours, with a slow fade after that. CBD side effects, when they happen, tend to pass within a few hours, though CBD stays in the body longer than most people expect.
THC is stored in fat tissue and can show up on a drug test for days to weeks after last use.
What are the serious risks?
Cannabis hyperemesis syndrome
Some long-term, heavy users develop repeated bouts of severe vomiting with stomach pain. Hot showers or baths often ease the symptoms, which is a hallmark of the condition. The only reliable fix is to stop using cannabis.
Mental health effects
High-dose THC can trigger panic attacks, paranoia, and brief hallucinations. Regular use of high-potency products is tied to a higher risk of psychosis in people who carry a genetic risk. Teens face more risk because their brains are still developing.
Heart and lung effects
Cannabis raises heart rate and can shift blood pressure, which matters for people with heart disease. Smoke holds many of the same irritants as tobacco smoke and is linked to chronic bronchitis. Anyone with chest pain, a racing pulse, or shortness of breath should get medical help.
Dependence and withdrawal
A share of regular users develop cannabis use disorder, and the risk climbs when use starts in the teen years. Withdrawal can bring irritability, insomnia, low appetite, and cravings that peak in the first week.
Who should avoid cannabis?
- People under 21, and under 25 for high-THC products
- Anyone who is pregnant or breastfeeding
- People with a personal or family history of psychosis or schizophrenia
- People with heart disease or uncontrolled high blood pressure
- Anyone taking drugs that interact with THC or CBD, including blood thinners and some seizure medicines
- People with a history of substance use disorder
Older adults should start low as well, since the body clears THC at a slower pace with age.
How can you lower your risk of side effects?
- Start with a low dose, then wait. With edibles, give it two hours before taking more.
- Check the THC content. Products with high THC percentages raise the odds of anxiety and paranoia.
- Skip mixing cannabis with alcohol, which multiplies impairment.
- Do not drive or run machinery for at least 4 hours after inhaling, and longer after edibles.
- Choose products with lab tests. A certificate of analysis shows THC and CBD levels plus any contaminants.
- Talk to a doctor if you take prescription drugs or have a heart condition.
Frequently asked questions
Can cannabis cause a panic attack?
Yes. THC can raise anxiety and trigger panic, most often with high doses or when you are already stressed. The feeling is intense but passes as the drug clears. Slow breathing, water, and a calm room help.
Does CBD have side effects?
CBD can cause drowsiness, diarrhea, appetite changes, and tiredness. It also interacts with drugs broken down by liver enzymes, including warfarin and some anti-seizure medicines. High-dose CBD is linked to liver enzyme changes in some users.
Can you overdose on cannabis?
A fatal cannabis overdose is not known to happen in humans. A bad reaction can still send you to the emergency room with vomiting, panic, or chest pain, and edibles are the usual cause.
Do side effects go away with tolerance?
Some do. Regular users report less anxiety and less memory fog, but tolerance also pushes people to use more, which can bring the effects back.
CBD products carry a shorter list of side effects than THC products in most cases. Shorter is not the same as none, so start low and track how you feel.