I really wouldn't know about essential oils, but

1) Especially lemon should be good for your skin in small amounts, but in long-term is a bit too strong. I'm not sure what it might cause, but I'd use lemon in moderation.
2) Citrus fruit tend to have more fungus than other fruit, and therefore are not that good for us. Yep, that also means the ah so yummy orange juice. And we all know fungus affects your candida balance negatively... I've dropped oranges from my diet completely. Doesn't even hurt.