A little, in predictable places, and only if you do nothing about it.
Will a body to body massage get oil in your hair? The route itself mostly stays below the neck. Broad contact travels the back, the legs, the arms and the front of the torso, and the head is not where the weight goes. But oil is generous stuff and hair sits right at the edge of the working area, so a few strands at the nape, a line along the hairline, and anything long enough to reach the shoulders will usually come away with a sheen.
Whether that matters depends entirely on what you are doing next.
Where does a body to body massage get oil in your hair?
The nape. Every pass that finishes at the shoulders ends here. Short hair at the back of the neck takes more oil than anywhere else on the head.
Behind the ears. Lying face down with your head turned, the upper ear sits close to the path of a forearm crossing the shoulder.
The hairline at the temples. Mostly while you are face up, when the hands travel up the neck and around the jaw to close the session.
Long hair. If it lies across the back, it is simply in the way of the massage, and it will be oiled as thoroughly as the skin underneath.
Beards. A beard resting on an oiled forearm or pillow picks some up. Most owners of one treat this as free conditioning.
Keeping oil out of your hair during a body to body massage
Long hair: tie it up high and loosely, well above the nape. A clip or claw works better than an elastic, because a knot at the back of the head presses into the pillow once you are face up. A loose bun placed on the crown keeps everything clear of the shoulders without pulling.
Shoulder-length hair: pin it up, or push it forward over the top of the head once you are face down. The therapist will usually move stray strands before a pass, but it is easier for both of you if they are already out of reach.
Short hair: nothing to do. Accept a little shine at the nape.
The scalp: whether the head itself is worked varies with the therapist and with what you ask for. If you want it, say so, and plan on washing your hair afterwards. If you would rather not, say that too, and the hands will stop at the neck.
A towel laid over the pillow keeps it clean either way. Hotel pillowcases are white, and oil marks show.
Hair products, extensions and colour
Styling wax, gel and hairspray transfer onto towels, pillows and skin once they meet warm oil, and a stiff, sprayed style will not survive lying down anyway. If you can, arrive at the session with product-free hair.
Extensions and hairpieces deserve a line in the booking message. Some attachment methods dislike oil, and your stylist will know which kind you have. Keeping them well clear of the shoulders, tied high and wrapped in a small towel, is the simple precaution.
Freshly coloured hair can bleed a little onto a white towel if oil soaks it in the first few days. One more reason to keep it up and away.
Washing it out
Oil and water do not mix, which is why a quick rinse leaves hair greasier than before. The method that works: apply shampoo to dry hair first, work it through the oily sections with your fingers, and only then add water and lather. Rinse, then shampoo a second time. Conditioner on the ends only, if at all.
That takes ten minutes in a hotel shower, fifteen with drying. If a table is booked, build it into the timing. After a body to body massage covers the rest of the hour that follows, including how most of the oil on the skin disappears on its own.
No time to wash? Dry shampoo worked into the nape absorbs enough to carry you through dinner, and hair tied back hides the rest.
If the technique is not oil
Gel and foam change the answer. Nuru gel does not sink in the way oil does, and warm water alone takes most of it out of hair. Soapy massage begins in the bathroom, where hair gets wet whatever you do; with that form, the question is not whether to wash it but when.
Planning around the evening
If the session is the last thing before sleep, do nothing at all. Oil at the nape overnight is harmless, and the morning shower deals with it. If the session comes before going out, tie the hair up, leave fifteen minutes, and shampoo dry first. Body to body massage tonight has more on fitting the hour around a meal or a late plan.
And if you are packing for the trip, what to wear for a body to body massage lists the other small things worth removing before lying down, from watches to hair ties that dig.