Cannabis Chemotypes and THC:CBD Ratios
Cannabis products differ in their proportions of tetrahydrocannabinol (THC) and cannabidiol (CBD). Understanding those proportions can help patients discuss potential effects and risks with their clinician.
What is a cannabis chemotype?
A chemotype classifies cannabis by its predominant cannabinoids. It describes chemical composition—not a guaranteed therapeutic effect.
| Chemotype | Typical composition | Clinical considerations |
|---|---|---|
| Type I — THC dominant | THC exceeds CBD | May have therapeutic applications, but carries greater risk of intoxication, dizziness, anxiety, and cognitive impairment. |
| Type II — Balanced | THC and CBD both substantial, often approximately 1:1 | Provides exposure to both cannabinoids. CBD does not reliably prevent THC-related adverse effects. |
| Type III — CBD dominant | CBD substantially exceeds THC | Allows greater CBD exposure with less THC, but THC-related impairment can still occur. |
Understanding THC:CBD ratios
Ratios are written in the order THC:CBD. A 1:3 ratio means that for every 1 mg of THC, the product contains 3 mg of CBD. A 1:10 ratio means 1 mg THC for every 10 mg CBD.
| THC per dose | CBD at 1:3 THC:CBD | CBD at 1:10 THC:CBD |
|---|---|---|
| 1 mg | 3 mg | 10 mg |
| 2.5 mg | 7.5 mg | 25 mg |
| 5 mg | 15 mg | 50 mg |
For cannabis-naïve or THC-sensitive adults, a clinician may discuss a CBD-dominant product, such as 1:3 to 1:10 THC:CBD, while keeping initial THC near 1 mg or another carefully selected low dose. The dose should be individualized rather than chosen from the ratio alone.
What does research show about chronic pain?
Some clinical trials and systematic reviews have found small short-term improvements in chronic pain with THC-containing or THC:CBD cannabis products compared with placebo. Evidence supporting CBD alone for chronic pain is weaker or frequently negative.
Current evidence does not establish that combining CBD with THC is consistently better than THC alone, or that one THC:CBD ratio is optimal for pain relief. Potential benefits must be weighed against dizziness, sedation, cognitive impairment, and other adverse effects.
Patient safety
Use the lowest effective dose under individualized clinical guidance. Do not drive or operate machinery while impaired. Avoid combining THC with alcohol or sedating medications. Discuss pregnancy, cardiovascular conditions, mental-health history, liver disease, and medication interactions with your clinician.
Review product laboratory testing when available. Label claims and cannabinoid concentrations may vary by product or batch.