Getting high from cannabis isn’t harmless, but it’s not equally risky for everyone. The effects depend heavily on your age, how often you use, the potency of what you’re consuming, and how you consume it. For occasional adult users, the acute risks are relatively modest. For teenagers, pregnant women, daily users, or people with a family history of psychotic disorders, the risks are substantially higher and backed by strong evidence.
What THC Does to Your Brain
THC, the compound in cannabis that produces the high, works by binding to receptors concentrated in areas of the brain that control memory, coordination, pleasure, and time perception. These receptors normally respond to naturally produced signaling molecules that help regulate how brain cells communicate. When THC floods those receptors, it disrupts the normal release of chemical messengers in the hippocampus (critical for forming new memories) and other regions, which is why being high makes it harder to learn new information, react quickly, or judge the passage of time.
The high itself typically peaks within 10 to 30 minutes when smoking, or one to three hours with edibles. During that window, your heart rate increases, your short-term memory is impaired, and your reaction time slows. For most healthy adults, these effects are temporary. The more important question is what happens with repeated use over weeks, months, or years.
The Age Factor
The single biggest risk factor for harm from getting high is how old you are when you start. The brain continues developing well into the mid-20s, and the wiring that connects different brain regions is still maturing throughout adolescence. Cannabis use during this period can interfere with that process. Brain imaging studies of teen users show measurable differences in the structural connections between the frontal and parietal lobes, areas responsible for decision-making, attention, and impulse control. These are association tracts that don’t fully mature until late adolescence, making them particularly vulnerable.
The average age of first use among adolescent cannabis users in research studies is about 14. According to federal survey data, 63% of new cannabis users are younger than 18 when they first try it. The CDC reports that the risk of developing cannabis use disorder is significantly greater for people who begin using before age 18. This isn’t a small effect: early use appears to raise the ceiling on nearly every other risk described below.
Dependency Is More Common Than Many Think
Cannabis is often described as non-addictive, but that’s not accurate. Approximately 3 in 10 people who use cannabis develop cannabis use disorder, according to CDC data. That’s a dependency rate of roughly 30%, which is lower than tobacco or heroin but far from negligible. Cannabis use disorder involves difficulty cutting back despite wanting to, withdrawal symptoms like irritability and sleep problems, and continued use even when it’s causing problems at work or in relationships.
The risk increases with frequency. Daily or near-daily users are at much higher risk than weekend users. Higher-potency products also appear to accelerate dependence, which matters given how much stronger cannabis has become.
Today’s Cannabis Is Much Stronger
The cannabis available in the 1990s averaged about 5% THC. Today, flower strains average 15 to 20%, with some reaching 35%. Concentrates like wax, shatter, and hash oil typically range from 60 to 90% THC. In Washington State’s regulated market, the average THC concentration for flower was 21% in 2022, and for concentrates it was 69%.
This matters because most of the older research on cannabis safety was conducted when the drug was far less potent. If you’re using modern concentrates, you’re consuming a fundamentally different product than what was studied in the 1970s or 1980s. Higher potency has been linked to greater dependency risk and a stronger association with psychotic episodes.
Cannabis and Psychosis
One of the most serious risks of regular cannabis use is its connection to psychosis, particularly for people who are genetically predisposed to schizophrenia. A study published in the British Journal of Psychiatry found that among cannabis users, those who preferred high-potency varieties had roughly 7 times the odds of experiencing a psychotic episode compared to those using lower-potency products (adjusted odds ratio of 6.8). In the study, 78% of people who had experienced psychosis used high-potency cannabis, compared to 37% of the control group.
This doesn’t mean everyone who gets high will develop psychosis. Most won’t. But if you have a close family member with schizophrenia or a psychotic disorder, or if you’ve ever experienced paranoid thoughts or hallucinations while high, your individual risk is substantially elevated.
Effects on Memory and Thinking
Regular cannabis use does impair cognitive function, particularly verbal learning, memory, and attention. The encouraging finding is that most of these deficits appear to be reversible. Research tracking users through monitored abstinence shows that verbal learning and memory tend to recover within one to two weeks of stopping. Attention and mental processing speed take longer, with some deficits persisting for three to four weeks before normalizing.
This recovery timeline applies primarily to otherwise healthy users. For adolescents whose brains are still developing, the evidence is less reassuring. Some structural changes observed in teen users may represent permanent alterations to brain wiring rather than temporary impairment.
Heart and Lung Risks
Getting high produces an acute spike in heart rate driven by a shift in your nervous system toward a “fight or flight” state. Research published in the European Heart Journal found that the risk of heart attack increases 4.8 times in the hour following cannabis use. That sounds alarming, but in absolute terms, cannabis triggers an estimated 0.8% of all heart attacks. For a young, healthy person, the baseline risk is so low that even a fivefold increase remains tiny. For someone with existing heart disease, the calculus changes significantly.
Smoking cannabis exposes your lungs to many of the same toxic particulates found in tobacco smoke. Vaporizing reduces that exposure, though the reduction in measurable lung harm is smaller than you might expect. Neither method is risk-free, but combustion is clearly worse for your airways.
Driving While High
Cannabis roughly doubles the risk of a motor vehicle accident. Two large meta-analyses, each reviewing nine epidemiological studies, found significantly increased crash risk with odds ratios of 1.92 and 2.66 after controlling for other variables. At higher blood THC levels (5 nanograms per milliliter or above), the crash responsibility odds ratio climbs to 6.6, which is comparable to driving with a blood alcohol concentration of 0.15%, nearly twice the legal limit for alcohol.
Driving impairment from cannabis is real, even if it manifests differently than alcohol impairment. The combination of slowed reaction time and impaired attention creates genuine danger, particularly in the first hour or two after smoking.
Pregnancy and Breastfeeding
THC crosses into breast milk in any form, whether smoked, vaped, or eaten as edibles. The CDC warns that these chemicals can affect a newborn’s brain development, potentially resulting in hyperactivity, poor cognitive function, and other long-term consequences. The same concern applies during pregnancy, when THC can reach the developing fetus. There is no established safe level of cannabis use during pregnancy or breastfeeding.
Putting the Risks in Perspective
For an adult over 25 who uses cannabis occasionally, doesn’t drive while high, and has no personal or family history of psychotic disorders, getting high carries real but relatively modest risks. The acute dangers are primarily cardiovascular and impairment-related. The longer-term concern is the roughly 1-in-3 chance of developing dependency with regular use.
The risk profile shifts dramatically for teenagers, daily users, people consuming high-potency concentrates, anyone with a predisposition to psychosis, and pregnant or breastfeeding women. For these groups, the evidence of harm is strong and consistent across multiple lines of research. If you’re in one of those categories, getting high carries meaningfully higher stakes than the casual framing of cannabis culture typically acknowledges.