lashuna :

Substitute:

Garlic powder has a different taste from fresh garlic. If used as a substitute for fresh garlic

Garlic chives, an herb with a garlicky flavor, are an obvious substitute

Adultrants:

garlic powder is adultered with chalk and talc

Controversy:

contrindications - Kaphaj and pittaj vikaras, agni mandya, old age, sutika (puerpera), Garbhini, shishu (child), aama rog (indigestion), jwara (fever), atisaara(diarrhea), kamala (jaundice), diseases of mukha and throat, shosha, immediately after vaman (emesis), virechana (purgation), nasya and basti .

Best ritu(season) to use lashuna is pausha and magha (hemant- shishir) i.e. in the month of December and January. Again its matra and use depends upon satmya, jatharagni (digestive power) and kaala (age/time period/ritu).