Although typically considered safe in small amounts, over consumption of propylene glycol is toxic to the body, and can lead to a buildup of lactic acid that causes acidosis and kidney failure. This is especially concerning with people who already have kidney or liver disease, as their process of clearing toxic substances is not as efficient. Pregnant women and infants are also at higher risk of developing toxicity if exposed to large amounts. There are also many people considered allergic to propylene glycol who may develop a rash when coming into contact with it. In others, it can cause digestive issues and discomfort such as bloating, gas, diarrhea, and stomach pain.