Birch tar oil has a distinct smoky, woody and slightly medicinal scent. This is not a perfumed shampoo, so do not expect a fresh salon fragrance. The smell is part of the formula and usually becomes weaker once the hair is rinsed and dried. If you rinse thoroughly, most people do not notice it strongly afterwards, although it can still be present close to the scalp immediately after the shower.
To keep the scent less noticeable, do not leave the shampoo on longer than needed. Massage it onto the scalp, allow it to work for a minute or two, and rinse with warm water. Air-drying in a ventilated room may help dissipate the smell faster. Conditioning the lengths can also help mask the aroma on the hair, though it does not remove the tar character from the scalp area.
If the smell bothers you, alternate this shampoo with your usual shampoo, or use it only on days when you feel the scalp needs a deeper wash. The tar scent is a common reason why tar-based products are chosen for practical cleansing purposes rather than for fragrance-led hair care. Keeping the jar closed after use also helps keep the product from spreading its smell through the bathroom.