Basically "safe use" of psychotropic substances is not possible. Even pharmaceuticals that undergo a rigorous approval will never be without side effects.
Herbal Incense mixtures normally consist of herbs without effects plus a synthetic cannabinoid responsible for the psychotropic effect. Generally, the consumer is not aware of the type or the amount of the added synthetic cannabinoid. Even if the presentation and merchandising creates an impression of clean product, the consumer should be aware that there exists no quality control.
Same product names do not necessarily imply that the added chemicals are identical in amount (quantity) or purity (quality).
During the manufacturing process there exists no o at most a very reduced quality control. In some analytical results synthesis residues were found or intensive odour of solvent was detected.
Burning always causes harmful substances. While with tobacco and cannabis, the compositions of the harmful substances are relatively well explored, there is no knowledge about the possible risks of smoking damiana (usually the main carrier of synthetic cannabinoids in herbal mixtures) and the contamination of the chemicals themselves. Further, it cannot be assumed that the solvents used to apply the cannabinoids, meet established pharmaceutical standards. Through the use of so-called "vaporizers", at least some of the harmful substances can be avoided, which emerge during smoking.
As some products are effective in very small amounts (1-5 mg), consumers should be very carefully in the application. By no means should be taken the full amount of an unknown substance. A companion that remains sober could help in emergencies.
Especially with intranasal consumption always use your own straw. Doing so, consumers can avoid hepatitis C virus infections.
In consumption always be aware of your mental constitution and the settings.
Hand off the steering wheel after consuming any drugs!
After extensive highs/intoxications the body should rest.