Essential oils are very concentrated substances and should never be used internally, unless you are following the advice of a properly certified and educated aromatherapist.
Oil and water do not mix. Essential oils should not be added to water (or other beverages) for flavoring, or any other reason. By doing this, even if you “mix” your drink well, you are ingesting tiny droplets of undiluted essential oils, which can cause harm to mucous membranes and internal body systems. Never use essential oils as a flavoring agent in your drink – use real fruit or herbs instead!
There seems to be a common misconception right now, that since essential oils are all-natural, they are without contraindications/hazards and are safe to ingest); well that is incorrect. Some mistakenly believe that if an essential oil is approved by the FDA and EPA as GRAS (generally recognized as safe); then it is safe to ingest internally. The GRAS designation applies to using the essential oils as food flavorings, not internally ingesting them as a form of medicine.
The only time essential oils should be ingested or used internally; is if you are under the guidance of a trained health care practitioner that is certified in aromatherapy and has training in oral administration of essential oils.
The four prior examples are just a small glimpse into the injuries that occur to well-meaning people, as a result of unsafe essential oil use – whether intentional or unintentional.
Who is properly trained and qualified to recommend ingesting essential oils?
The following info-graphic goes into more details about who is qualified to recommend internal usage of essential oils.