Essential Oils Safe for Internal Use by the FDA (GRAS)

Look for oils that are GRAS, which is the FDA-approved list of oils that are Generally Recognized As Safe for internal use. A complete list can be found here:

Essential Oils Found on the GRAS List:
Basil (Ocimum basilicum)
Bergamot (Citrus bergamia)
Black Pepper (Piper nigrum)
Cassia (Cinnamomum cassia)
Cinnamon (Cinnamomum zeylanicum)
Clary Sage (Salvia sclarea)
Clove (Eugenia caryophyllata)
Coriander (Coriandrum sativum)
Cumin (Cuminum cyminum)
Fennel (Foeniculum vulgare)
Geranium (Pelargonium graveolens)
Ginger (Zingiber officinale)
Grapefruit (Citrus X paradisi)
Juniper Berry (Juniperus communis)
Lemon (Citrus limon)
Lemongrass (Cymbopogon flexuosus)
Lime (Citrus aurantifolia)
Marjoram (Origanum majorana)
Melissa (Melissa officinalis)
Oregano (Origanum vulgare)
Peppermint (Mentha piperita)
Petitgrain (Citrus aurantium)
Roman Chamomile (Anthemis nobilis)
Rosemary (Rosmarinus officinalis)
Spearmint (Mentha spicata)
Tangerine (Citrus reticulate)
Thyme (Thymus vulgaris)
Wild Orange (Citrus sinensis)
Ylang Ylang (Cananga odorata)