I realize now how important that information was, after speaking with a handful of other patients and even dispensary agents who have complained that the tincture drops burn under their tongues. My response is always that cannabis tinctures should not burn if they are being used properly.
There are two main types of tinctures: glycerin-based and alcohol-based. Only glycerin tinctures can be used as drops in the mouth or under the tongue and they do not burn. Glycerin-based tinctures actually taste kind of sweet. Alcohol-based tinctures are intended to be added to either cold or hot drinks. They will burn if dropped directly under the tongue or in the mouth. Alcohol-based tinctures also contain inactive THC in the form of THCa. This means that when the tincture is dropped in a cold beverage, there are no psychoactive effects. However, when dropped in a hot beverage the THCa is converted into the psychoactive cannabinoid THC. It should be noted that glycerin tinctures already contain active THC because of how it is processed. You can learn more about both THC and THCa in our cannabinoid article.
Cannabis tinctures are great because they allow for easy dosage control and can be consumed discreetly. Alcohol tinctures also give patients the option of psychoactive effects. CBD tinctures are also on the market, but patients should be wary because some of these products contain very low doses of CBD combined with sugars and therefore can have little to no benefit. Tincture buyers should look to find out the quantity of cannabis and even the strain or at the very least the variety (Indica, Sativa, Hybrid) used to get the most understanding of the medicinal marijuana product they are using. Some tincture manufacturers do have their products tested so the cannabinoid percentages are marked as well. I would recommend steering away from tinctures which are not marked with the cannabis content.
Hopefully by sharing this information, others can avoid the tincture burn in the future!