I will quote from the Vets Tips For Fanciers Quote Can garlic and probiotics be used together? I thought garlic was a natural antibiotic and would kill the probiotic bacteria. The main alkaloid of garlic is allicin. Allicin has a strong antibacterial effect against e.g. streptococci, staphyococci, pseudomonas and coli. it has an antiparasitic and antifungal effect, as well.These bacterial and parasites have certain enzymes that contain sulphur - the allicin, destroying these enzymes, can kill bacteria and parasites. Allicin destroys the enzymes of beneficial enterococci, too, depopulating bowel bacteria. In addition, active ingredients of garlic help digestion, thus preventing the development of illnesses caused by undigested foods. They boost the immine system and neutralize the free radical scavengers so that they strengthen the whole body. It is not accidental that the methodical use of garlic extract increases the yield of chickens and other poultries by about 10%. It is very important, as garlic is a natural substance, and so in many cases we can avoid the use of antibiotics. But like anything else, garlic can be overdosed. In too great quantities garlic destroys the majority of beneficial bowel flora and can cause a sterile inflammation in the intestinal canal. So overdose of it should be avoided. Keeping all these considerations in mind, in my opinion it is beneficial to give probiotics after using garlic. I conducted a simple laboratory experiment for this topic. I took a culture medium used to make bacteria grow, a slice of garlic, one drop of pure water and a very little amount of a certain probiotic containing several strains of beneficial intestinal bacteria.