WHAT IS THE BEST WAY TO USE CANNABIS?
Cannabis and its extracts, like CBD oil, can be consumed in an astounding number of ways. Most options fall into a few general categories, and each has its own advantages and disadvantages. You’ll experience different effects if you smoke CBD-rich flower or vape a THC-rich cartridge; swallow a gelcap or drop CBD oil under your tongue.
The key differences between ways of using cannabis pertain to these questions:
1. Onset: How quickly will cannabinoids begin to work?
2. Dose: What’s a reasonable starting dose?
3. Distribution: Which parts of the body will be most affected?
4. Duration: How long will the effects last?
INHALATION: SMOKING AND VAPING
• Onset: Seconds to minutes.
• Dose: As little as a puff may be necessary. A typical joint is 0.3 – 1.0 grams of cannabis.
• Distribution: Affects the lungs immediately, then the heart and brain, then is distributed fairly evenly throughout the body.
• Duration: Most effects, including psychoactivity, subside after 2-3 hours.
When drugs are inhaled through the lungs, they are sent to the brain before getting metabolized by the liver. This makes inhalation the fastest method for administering cannabis. Usually, between 20-30% of the phytocannabinoids like THC and CBD are absorbed this way. The heat from either smoking or vaporizing cannabis converts the acid cannabinoids into their neutral forms.
SMOKING VS. VAPING, BUD VS. OIL
One inhales cannabinoids by smoking or vaporizing flowers. Cannabis oil extracts can also be vaporized or dabbed. The main issue with smoking is that smoke is harmful to the lungs. Although smoking cannabis is not associated with lung cancer or COPD, there are health issues associated with breathing any kind of smoke (e.g. chronic cough, congestion, asthma). The cannabinoid tetrahydrocannabivarin (THCV) appears not to vaporize well, so smoking or non-inhaled administration methods may be necessary to get benefits from THCV.
EDIBLES / CAPSULES
• Onset: 1-2 hours.
• Dose: The threshold for mild psychoactive effects is 3 mg THC in most new users. Doses of CBD-rich products range from 5 mg to hundreds of milligrams. 
• Distribution: Absorbed through the gut and modified in the liver, then spreads fairly evenly throughout the body.
• Duration: Psychoactive effects subside after about 6 hours in most people. Other effects may last up to 12 hours.
Ingested cannabinoids are absorbed through the intestines and sent to the liver. It takes about an hour to feel effects when taken on an empty stomach, or up to three hours with food. People should not re-dose THC edibles for at least three hours after ingestion.
Read more at article PROJECT CBD