The short answer: for most adults, cannabis is not the worst thing you can put in your body, but daily use of high-THC products is where the long-term problems show up. Reddit threads land somewhere between "it ruined my life" and "I have smoked for 20 years and I am fine." Both are real experiences. Neither one is a study.

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Why Reddit answers pull in both directions

Ask this in a weed subreddit and you hear from people who love cannabis, people who quit because it went badly, and a lot of people in between. That is a biased sample in two directions at once. The person who uses a few times a month and never thinks about it does not post. Neither does the person who had one rough edible and moved on. You mostly hear from the extremes, which is why the thread feels contradictory.

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What Reddit is genuinely good for: descriptions of withdrawal, sleep problems after quitting, and what daily use feels like from the inside. What it is bad at: estimating your risk. Nobody in the comments knows your dose, your THC percentage, your age of first use, or your family history.

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What the research actually shows

Dependence and withdrawal

About 1 in 10 adults who use cannabis will meet criteria for cannabis use disorder at some point, and that climbs toward 1 in 6 when use starts in the teen years, according to NIDA. Daily users report irritability, insomnia, low appetite, and cravings when they stop. It is not alcohol withdrawal, but it is not nothing either.

is cannabis bad for your brain development

Lungs

Smoking anything delivers tar and irritants. Cannabis smoke carries many of the same combustion products as tobacco smoke. The American Lung Association notes that regular cannabis smoking is linked to chronic bronchitis, chronic cough, and phlegm. Whether cannabis-only smoking causes lung cancer is still unsettled, mostly because studies struggle to separate it from tobacco. Vaping skips combustion but brings its own unknowns, especially with unregulated cartridges.

Mental health

This is the part Reddit argues about most. The evidence points to a link between high-potency cannabis and psychotic disorders, strongest among daily users and people who started young. A widely cited London study found that daily use of high-potency cannabis was associated with much higher odds of psychotic disorder compared with never using. Association is not causation, and most people who use cannabis never develop psychosis. But if you have a personal or family history of schizophrenia or bipolar disorder, this is the risk I would take most seriously.

Anxiety and depression links are murkier. Cannabis can calm you in the moment and worsen anxiety over months of daily use. Plenty of people quit and find their baseline mood improves.

Memory, focus, motivation

Acute effects on short-term memory and attention are well documented. Heavy long-term users tend to show small differences on attention and memory tests, though it is hard to separate cannabis from sleep, alcohol, and everything else. The "amotivation" stereotype is overstated, but "I stopped doing things I used to enjoy" shows up in quit threads constantly.

Cannabinoid hyperemesis syndrome

Less known and genuinely nasty. CHS causes recurring severe nausea and vomiting in some long-term heavy users, and the tell is compulsive hot showers. Mayo Clinic lists it as a real complication, and the only reliable fix is stopping.

Other risks worth knowing

Dose, potency, and age matter more than the plant itself

Almost every long-term risk scales with frequency, THC percentage, and how early you started. Occasional use of a moderate-THC flower product looks very different from daily dabs or a gram of 30% flower before bed. If you plan to use long term, the variables you control are how often, how strong, and whether you smoke it.

If you plan to use long term, here is my checklist

  1. Track frequency for two weeks. Daily use is the line where most risks jump.
  2. Know your THC percentage. Edibles and carts often hit harder than flower.
  3. Take a tolerance break and see how you feel. Withdrawal symptoms are information.
  4. Watch mood and sleep, not just whether you enjoy it.
  5. Skip it if you have a family history of psychosis, are pregnant, or are under 25.
  6. Tell your doctor. They ask about alcohol, and cannabis is no different.

Bottom line

Cannabis is not harmless and it is not the catastrophe some headlines suggest. The long-term downsides are dose-dependent and concentrated in daily high-THC use. Reddit can tell you what it feels like. It cannot tell you your risk.