Abstract
The removal of cannabis plants from the list of Category 5 narcotic drugs in 2022, which
included permission to grow, sell, and use cannabis beyond medical purposes, necessitates
close and continuous monitoring of the number of users and health impacts, particularly the
health costs arising from cannabis-related illnesses in the Thai population. This includes
surveying shops that sell cannabis and cannabis products available for consumption
nationwide. This study was conducted as a project series, partly using data from the Centre
for Addiction Studies (CADS), which conducted a survey on the attitudes and behaviors of drug
use among Thais aged 18-65 years in 20-30 provinces across all regions of the country. It was
found that the prevalence of recreational cannabis users in the past 12 months has
significantly increased, especially in 2022, with a proportion as high as 24.9%, an increase of
487% compared to the previous year. The proportion of medical cannabis users, although
increasing, was still only 2.59% in 2023, with a growth rate of 109% and 122% in 2022 and
2023, respectively. An analysis of the estimated total cost of illnesses, including both
outpatient and inpatient cases and indirect costs from lost work opportunities of patients with
psychiatric disorders due to cannabis use (F12), assuming that the proportion of patients with
psychiatric disorders from cannabis use is 8%, found that the total costs were not more than
2 billion baht per year from 2019-2021. However, this sharply increased in 2022 to a value as
high as 10.222 billion baht, with inpatient medical treatment costs, outpatient medical
treatment costs, and indirect costs being 6.736 billion baht, 749 million baht, and 2.736 billion
baht, respectively. Additionally, a supply-side survey examining cannabis beverages, which are
easily accessible products, by testing the levels of delta-9-tetrahydrocannabinol (∆9-THC)
found that out of 207 samples nationwide, 42.51% contained ∆9-THC, and six samples had
more than 1.6 mg per glass, which could affect consumer health. A study of shops in Silom
Road and Khao San Road areas revealed that cannabis retail shops are located in commercial
areas, visible and near entertainment venues. The shops are categorized into four types: large
shops, medium shops, standalone shops, and stalls. The size of the shop affects the cannabis
sales practices, price, and quality. However, legal compliance in each shop, such as safety
standards, prevention of youth access, types of cannabis products sold, promotional activities,
shop condition, and location, was only partially followed. The health equity impact
assessment on vulnerable groups found more negative than positive impacts.
In summary, the policy change to allow easier access to cannabis use in 2022 led to a sharp
increase in cannabis users, patients, and costs associated with cannabis-related psychiatric
illnesses. Even though this study did not consider the long-term mental health costs of
cannabis addiction, tracking patients over time could lead to more accurate cost calculations.
Moreover, some cannabis products have active ingredient levels above recommended limits,
and shops only partially comply with legal guidelines. Therefore, it is proposed to issue
ministerial regulations to bring cannabis plants under narcotic control laws again, aligning with
the survey results where the majority of the Thai population supports the idea of reclassifying
cannabis as a narcotic, allowing its use only for medical purposes to reduce health impacts
and costs. Further measures to restrict its use to medical purposes can be developed, such
as zoning, license restrictions, shop supervision, and legal penalties.
