A blog graphic for the Cannabis Side Effects article

TL;DR:

Mild effects: dizziness, nausea are common.
Serious reactions: psychosis-like episodes, heart rhythm changes (rare).
Hospital/ED visits: up 120% since 2007.
Safety tip: Start ≤2.5 mg THC; store edibles securely.

Health Canada received 631 reports of side effects from legal cannabis products between 2018 and 2023 — a nearly 5-fold increase since legalization.1 While legalization aimed to reduce harm and control quality, it also introduced new safety challenges that continue to evolve.

This article breaks down Health Canada and CIHI data from 2018 to 2025 into clear, practical guidance for recreational users. We cover national adverse reaction reports, hospital and emergency data, the role of edibles and high-THC products, harm-reduction strategies, and how to report problems.

Whether you’re a first-time consumer or a frequent user, understanding these insights can help reduce risks and improve outcomes.

1. National Side-Effect Reports (2018–2023)

Between 2020 and 2023, reported cannabis side-effects to Health Canada dropped from 287 to 128 total reports.2,3 However, this decline in formal reports may not reflect the true extent of cannabis-related harms.

Why the gap?

Voluntary reporting by consumers and healthcare providers means many cases likely go unreported.
Hospitalizations and ED visits, which are captured independently, are still rising, suggesting that many users seek medical help directly instead of reporting via Health Canada channels.

In 2023, over half (52%) of legal product-related reports were considered serious. The most frequent reason? “Other medically important condition.”

Year	Total Reports	Unique Legal Cases	% Serious Cases	Top Seriousness Reason
2020	287	159	Not stated	Mostly for medical use
2021	260	174	60%	Medically important condition
2023	128	56	52%	Medically important condition

Oral consumption, especially via edibles and oils, was the most common route in pediatric cases.

2. Hospitalizations & Emergency Visits (2007–2020)

While formal side-effect reports decreased, hospital data tells a different story. Between 2007 and 2020,4 cannabis-related:

Hospitalizations increased by 120%
ED visits rose by 88%

In 2020 alone, there were:

5,318 cannabis-related hospital stays
37,341 ED visits

Key health drivers:

Neuropsychiatric issues like psychosis, hallucinations, and paranoia
Unintentional injuries, especially among children and older adults

Youth aged 0–14 saw the largest spike in cannabis-attributable hospitalizations:

+247% for girls, +226% for boys

Even seniors weren’t spared. Hospitalization rates rose 48–107% in those aged 65+.

3. Top Adverse Reaction Categories

Side-effects vary, but patterns are clear:

Most Common Individual Events (Legal Products)

Symptom	2020	2021	2023
Hallucinations	52	60	—
Dizziness	13	15	5
Nausea	12	21	—
Headache	—	17	7
Vomiting	—	—	5
Anxiety	—	—	3

Top System Organ Class (SOC) Categories – 2020

Category	% of Cases
Psychiatric disorders	23%
Nervous system disorders	15%
Gastrointestinal disorders	13%
General/administration site conditions	15%

Key takeaway: Psychiatric symptoms are the most common reason people report serious cannabis side-effects.

4. Age & Vulnerable Populations

Cannabis doesn’t affect all age groups equally. Certain populations face significantly higher risks due to physiological vulnerability or pre-existing conditions. Canada’s health data shows that youth, older adults, and pregnant individuals are among the most affected, often in ways not immediately visible in casual use.

Youth (under 25)

Despite stable overall use rates in recent years, youth remain at high risk for long-term mental health consequences. Cannabis can disrupt brain development until at least age 25 — affecting memory, decision-making, and emotional regulation.

Risks include:

Psychosis
Schizophrenia
Long-term memory and decision-making deficits
Higher addiction risk (1 in 6 if cannabis use starts in adolescence)

A 43% increase in edible cannabis use among teens was reported following the legalization of “youth-friendly” edibles like chocolates and gummies.5

This was accompanied by a 34% rise in cannabis smoking and 28% increase in cannabis + alcohol co-use.

Most alarmingly, this period also saw a sharp rise in paediatric emergency room visits, particularly for cannabis poisoning from edibles.

Adults Aged 35–64: A Silent Spike

Older adults are often left out of cannabis safety conversations, but hospital records show this group is seeing substantial increases in cannabis-related harms.

Between 2019 and 2020, hospitalizations for cannabis-related issues rose by 38% in adults aged 35–64.4
Common causes include unintentional injuries, psychotic episodes, and complications involving pre-existing health conditions.

This demographic is also more likely to have underlying cardiovascular issues, which can be aggravated by cannabis use, especially high-THC products.

Pregnant and breastfeeding individuals

Health Canada is unequivocal:

There is no known safe amount of cannabis during pregnancy or breastfeeding.6

Cannabis use can:

Affect fetal brain development
Increase the risk of low birth weight and developmental delays
Lead to poor feeding and drowsiness in breastfed infants

Health Canada advises zero use during pregnancy or breastfeeding.

5. Edibles, Extracts & High-THC Trends

Edibles pose some unique risks. Although they’re often marketed as a “gentler” or more discreet way to consume cannabis, their pharmacology and packaging make them one of the most common causes of accidental overconsumption, especially among inexperienced users and children.

Delayed onset (30 mins–2 hrs) → Edibles have a delayed onset of 30 minutes to 2 hours, sometimes longer depending on the individual’s metabolism, what they’ve eaten, and other factors.
Long duration → The full effects can take up to 4 hours to peak, and the intoxication can last 6–12 hours, with residual effects lasting into the next day.
Stronger effects → Liver converts THC to 11-hydroxy-THC, which is more intoxicating

The Legal 10 mg THC Limit (and Why It’s Still a Problem)

Canada’s Cannabis Regulations mandate that each edible cannabis product sold legally may contain a maximum of 10 mg of THC per package. However, this rule doesn’t always mean a single, clearly dosed item.

Many legal products come in multi-piece packs — for example:

A chocolate bar split into 5 pieces (2 mg each)
Gummies packaged as 4 x 2.5 mg pieces

Microdose Chart for Edibles

THC Dose	Effects	Recommendation
2.5 mg	Mild, beginner-friendly	Start here
5 mg	Moderate high, more intense	Wait 2+ hours to feel
10 mg	Strong effects, long-lasting	Not for first-timers

6. Harm-Reduction Checklist (Canada 2025)

Explore our low-potency starter bundle →

To reduce the risk of side effects, accidents, and long-term harm, follow these evidence-based safety tips endorsed by Health Canada and other public health authorities:

Check THC/CBD content on the label
Always read product labels carefully. Look for the exact THC and CBD amounts, and avoid unlabelled or homemade products where potency is unknown or inconsistent.
Start low (≤20% THC flower, ≤2.5 mg edibles)
First-time or infrequent users should start with low-THC products. For edibles, begin with no more than 2.5 mg of THC and wait at least 2 hours before redosing.
Don’t mix cannabis with alcohol or sedatives
Combining cannabis with alcohol, opioids, or anxiety medications increases the risk of over-sedation, impaired judgment, and serious accidents. Avoid poly-substance use to stay safe.
Store edibles in child-proof containers
Keep cannabis products locked away, out of reach and sight of children. Store in original, child-resistant packaging and never leave edibles out in kitchens or fridges.
Avoid cannabis while pregnant or breastfeeding
THC crosses the placenta and is found in breast milk. It may harm fetal brain development or cause feeding and developmental issues in breastfed infants.
Skip driving or operating machinery after use
Cannabis impairs reaction time, attention, and coordination. Even if you feel “okay,” residual effects can last 24 hours and significantly increase accident risk.
Use legal products only (regulated, labeled, child-resistant)
Legal cannabis products are tested for potency and contaminants, and come in standardized packaging. Illegal or homemade products may contain unsafe levels of THC or harmful additives.
If smoking, avoid holding breath or deep inhalation
Inhaling deeply or holding smoke increases toxin absorption without improving effects. Take shallow puffs and consider vaping or edibles as lower-risk alternatives.
Avoid frequent use (daily or almost daily)
Frequent cannabis use raises the risk of dependence, memory problems, anxiety, and psychosis. Take regular breaks and monitor your mental and physical well-being.
Educate yourself with reliable sources
Stay informed using evidence-based resources from Health Canada or provincial health authorities. Avoid relying on anecdotal advice or misinformation found on social media.

“Start low, go slow” isn’t just a saying — it’s the cornerstone of cannabis safety in Canada.

7. When to Seek Medical Help

Call 911 or Poison Control immediately if you or someone else experiences:

Chest pain or rapid heartbeat
Hallucinations or delusions
Loss of consciousness or seizures
Persistent vomiting
Respiratory trouble
Confusion, severe anxiety, or psychosis

Special Case: Cannabinoid Hyperemesis Syndrome (CHS)

CHS is a condition marked by:

Cyclical vomiting
Severe abdominal pain
Relief only with hot showers
Recovery only through complete cessation of cannabis

Reminder: Naloxone (used for opioid overdoses) does not work for cannabis-related incidents.

8. How to Report a Side-Effect

If you or someone else experiences an adverse effect from cannabis:

Steps to report:

Save product packaging (with batch number and details)
Visit Health Canada’s Cannabis Reporting Form
Provide:
- Age, sex, medical history
- Product type and seller (if known)
- Symptoms and outcomes
Upload photos or documents if needed

Reporting helps regulators identify dangerous products and issue recalls. Your input directly contributes to safer public use.

9. FAQs

Can you overdose on cannabis?

Not fatally, but yes, you can consume too much. Symptoms may include confusion, paranoia, fast heartbeat, hallucinations, and nausea.

Does CBD have side effects?

Yes. In high doses, diarrhea, fatigue, liver issues, and drug interactions are possible. Avoid during pregnancy or if taking medications.

Are hospital visits still rising?

Yes — hospitalizations and ED visits increased significantly from 2007–2020. Rates plateaued in 2021–2023 but remain high.

How long do side effects last?

Smoked: Peak at 30 mins, last ~6 hrs
Edibles: Peak at 2–4 hrs, last up to 12 hrs
Residual effects may persist 24+ hours

Compliance & Disclaimer

This article is for informational purposes only and is not medical advice. Always consult a qualified healthcare provider regarding cannabis use.

Staying Safe While Exploring Cannabis in Canada

Cannabis use in Canada has evolved rapidly since legalization — but so have the challenges around public health, product safety, and consumer awareness. While most side effects are mild, serious outcomes like psychosis, accidental pediatric ingestion, and hospitalisation are real concerns, especially with high-THC products and edibles.

At GetKush, we believe that quality cannabis should be accessible, trustworthy, and responsibly enjoyed.

As one of Canada’s leading online dispensaries, we offer a wide selection of products, including THC flower, edibles, and high-grade extracts.

Ready to explore premium cannabis with confidence?

Browse our curated collections now at GetKush

References:

Public. “Key Findings – Cannabis-Related Side Effects — Canada.ca.” Canada.ca, 2018, health-infobase.canada.ca/cannabis/side-effects/.
“Data on Cannabis Adverse Reactions: 2020 Annual Report.” Www.canada.ca, 16 Dec. 2022, www.canada.ca/en/health-canada/services/publications/drugs-health-products/data-cannabis-adverse-reactions-2020-annual-report.html.
Canada, Health. “Data on Cannabis Adverse Reactions: 2023 Annual Report – Canada.ca.” Canada.ca, 2023, www.canada.ca/en/health-canada/services/publications/drugs-health-products/data-cannabis-adverse-reactions-2023-annual-report.html.
Malam, Raadiya, et al. “Trends in Cannabis-Attributable Hospitalizations and Emergency Department Visits: Data from the Canadian Substance Use Costs and Harms Study (2007–2020).” Health Promotion and Chronic Disease Prevention in Canada, vol. 45, no. 6, June 2025, pp. 265–276, https://doi.org/10.24095/hpcdp.45.6.01. Accessed 20 June 2025.
Beard, McKenzie. “The “Quite Scary” Reality ER Docs Are Seeing as Teen Cannabis Edible Use Rose by 43% amid Legalization.” New York Post, 18 Apr. 2025, nypost.com/2025/04/18/health/teen-weed-edible-use-is-up-er-doc-warns-of-scary-reality/.
Canada, Health. “Thinking about Using Cannabis before or during Pregnancy?” Aem, 17 Oct. 2018, www.canada.ca/en/health-canada/services/drugs-medication/cannabis/health-effects/before-during-pregnancy.html.