externalsmile. Please be careful with using 4 oils together. It is recommended that you only use 3 together at one time. I suggest you take one of them out of the blend, the Roman Chamomile is the one I would take out, as you are drinking the tea.
seedling. It is not recommended to take essential oils internal, very rarely is this done. It is used in the food industry and in certain food dishes, but the dilution is a lot more than what you are using. The International Federation Of Aromatherapists, actually advise against this method.
Oregano ad Thyme are on the GRAS list, (Generally Regarded As Safe), but make sure they are pure essential oils, and the recommended dilution for taking them internally is to dilute 1 drop of oil into 1 teaspoon of oil soluble liquid. Such as Honey or full fat milk, the gel capusals can be used, as long as they are the larger ones and 1 oil per capsule.
There is not enough safety data to be able to say to anyone that they are 100% safe to take internally.
I personally would not use them internally. Unless maybe in cooking where the dilution is enormous.
Amethist