Short answer
Cannabis reduces chronic back pain for some adults. Products that contain THC have the strongest evidence. Start at 1 mg to 2.5 mg of THC, wait two hours, and stop if pain does not change. Cannabis does not repair discs, joints, or nerves.
Start low and go slow
Take 1 mg to 2.5 mg of THC for the first dose. Wait at least 2 hours before the next dose. Add 1 mg to 2.5 mg per step. Keep a log with dose, time, route, and a pain score from 0 to 10. Most patients in chronic pain trials used 1 mg to 20 mg of THC per dose. Doses above 20 mg raise the risk of dizziness, anxiety, and a fast heart rate.
Choose a route
- Inhalation (flower or vape): onset in 1 to 10 minutes. Peak at 15 to 30 minutes. Lasts 2 to 4 hours.
- Oral (edible, capsule, oil): onset in 30 to 90 minutes. Peak at 2 to 4 hours. Lasts 6 to 8 hours. Food in the stomach slows onset.
- Sublingual tincture: onset in 15 to 45 minutes.
- Topical: little THC reaches the blood. Evidence for back pain is weak.
Inhalation gives fast feedback, so titration is easier. Oral doses last longer and cover a full night of sleep.
THC, CBD, and ratios
CBD alone has not shown a clear benefit for back pain in controlled trials. A 1:1 THC to CBD ratio is common for daytime use. CBD blocks the CYP3A4 and CYP2C19 enzymes. This can raise blood levels of other drugs, including clobazam, warfarin, and tacrolimus.
Check for red flags
See a clinician before you self-treat if back pain comes with any of these signs: loss of bladder or bowel control, numbness in the groin or saddle area, fever, weight loss with no cause, cancer history, a recent fall, or weakness in both legs. Cannabis does not treat infection, fracture, or spinal cord compression.
Side effects and drug interactions
Common effects include dizziness, drowsiness, dry mouth, slower reaction time, and short-term memory problems. THC raises heart rate for 1 to 2 hours. Use caution with heart disease. Mixing cannabis with opioids, benzodiazepines, or alcohol raises the risk of sedation. About 9 percent of adults who use cannabis develop a use disorder. Do not drive after use.
Legal facts
Cannabis is a Schedule I drug under federal law. State rules cover possession, sales, and home grow. A medical card changes limits and taxes in some states. Check your state program before you buy.
What the evidence shows
A 2017 National Academies report found substantial evidence that cannabis or cannabinoids reduce chronic pain in adults. Cochrane reviews rate the evidence for cannabis-based medicines in chronic pain as low to moderate certainty. The FDA has approved no cannabis product for back pain.