As a general rule, I would say that this is not 100% necessary. However the answer is as ever, it depends. If receiving treatment for cancer, the answer is in my opinion always, “yes.” Indeed, if receiving treatment for any life threatening condition I would say the answer should be yes, though to be fair, an aromatherapist or other complementary practitioner should also be ensuring medical acceptance of their involvement and not relying on a vulnerable person to make a sensible decision.
My thinking about this was prompted by this article suggesting that in America 53 percent of post-menopausal women seek complementary or alternative remedies for their symptoms. The article’s main point of concern is interactions between medical drugs and herbal supplements/remedies. Here, there is a real danger of either overdosing or underdosing because of effects on absorption. The other danger is overdosing because the herbal remedy has a similar mode of action to a medical drug. Two examples of this spring to mind, SSRI antidepressants with St. John’s Wort (This is not an issue when using an infused oil from the leaves.) and willow bark with Non-steroidal anti inflammatory drugs such as aspirin.
With essential oils, a potential interaction is with drugs that cause photo-sensitivity. (This is true of a number of anti psychotic medicines.) Those taking these medications may be more likely to ignore advice on staying out of the sun after a massage and if citrus or other oils with this risk are used alongside these medications, serious sunburn could result.
I should point out that the main thrust of the article is not anti-complementary or Alternative medicine but rather that General Practitioners should be better informed and able to discuss these remedies with their patients.
I would also say that any complementary practitioner should always ask explicitly whether a client is having treatment from their GP either for the same problem they have come to the practitioner with or for something else. If the practitioner can not be sure that there will be no potential problems from interaction between their treatment and a medical one they should with the client’s permission seek medical approval.