What We Don't Know About Vaping THC Liquids Could Be Dangerous | Research

The takeaway

No human studies have characterized the pharmacokinetics of vaping THC in liquid form — a critical knowledge gap given these products are more potent than smoked cannabis and are rapidly growing in popularity.

Cannabis vapers, public health officials, regulators, and pharmacology researchers

What the researchers found

No human PK/PD studies exist for vaped liquid THC despite growing prevalence; analysis suggests these products may be more potent than smoked cannabis but consumer behavior may modulate delivery, creating an unpredictable risk profile.

Why it matters

Millions of people are vaping THC liquids without any scientific understanding of how these products deliver THC to the body — potency, timing, and peak effects remain entirely uncharacterized.

The numbers in context

Zero human PK/PD studies on vaped liquid THC found in PubMed or Embase; products are generally more potent than smoked cannabis flower.

How the study worked

Narrative review searching PubMed and Embase, synthesizing knowledge from smoked cannabis and nicotine e-cigarette research to hypothesize about vaped liquid THC pharmacology and identify regulatory implications.

What this study cannot tell us

Review identifies the knowledge gap but cannot fill it; hypotheses based on smoked cannabis and nicotine vaping may not accurately predict liquid THC vaping behavior; US regulatory focus may not apply globally.

How to read the evidence

Comprehensive review identifying a critical evidence gap, but cannot provide direct evidence on vaped THC pharmacology due to the absence of primary studies.

When this study was published

Published in 2026, underscoring that the THC vaping market has outpaced scientific knowledge.

The bigger picture

This represents a massive regulatory blind spot — THC vape products are being sold and consumed at scale with less pharmacological characterization than virtually any other commonly used psychoactive substance.

Questions still open

How do vaping device settings affect THC delivery? Do consumer self-titration behaviors make high-potency vape products safer or more dangerous than expected?

Common questions

Is vaping THC different from smoking cannabis?

Likely yes — THC vape liquids are generally more potent, but no human studies have actually measured how THC is absorbed, how quickly it peaks, or how long it lasts when vaped in liquid form.

Is vaping THC safe?

The honest answer is we don't know — the complete absence of human pharmacokinetic data means we can't characterize the risk profile. This is a major gap given how widely these products are used.

Read the original research

Vaping Δ9-tetrahydrocannabinol (Δ9-THC) in liquid forms: pharmacokinetics, pharmacodynamics, and regulatory implications.

Expert review of clinical pharmacology, 1-16

View on PubMed ↗Publisher’s paper ↗

Citation

Block, Ashleigh C; Smith, Danielle M; Goniewicz, Maciej L. (2026). Vaping Δ9-tetrahydrocannabinol (Δ9-THC) in liquid forms: pharmacokinetics, pharmacodynamics, and regulatory implications.. Expert review of clinical pharmacology, 1-16. https://doi.org/10.1080/17512433.2026.2630756