Crystal Meth is said to stay in your system for 48-72 hours. With some people crystal meth may remain in their system for up to 5 days. Breast Milk directly reacts from foods and medications consumed by the mother. In result, breast milk will contain the drug crystal meth for at least 48 hours and possibly up to 5 days. Any breast feeding would pass the crystal meth to the child nursing during that period of time.