doTERRA On Guard, a proprietary essential oil blend, provides a natural and effective alternative for immune support when used internally.* As one of doTERRA’s best-selling blends, doTERRA On Guard protects against environmental and seasonal threats with essential oils known for their positive effects on the immune system when ingested.* doTERRA On Guard can be taken internally on a daily basis to maintain healthy immune function.* It can also be used on surfaces throughout the home as a non-toxic cleaner. When diffused, doTERRA On Guard helps purify the air, and can be very energizing and uplifting.