A great deal of scientific work has shown the negative influence of tobacco smoke on the health of the entire body. A figure among all reminds us that for every week of smoking (20 cigarettes a day starting from 25 years of age) a day of life is lost on average.
The negative effects of smoking are also felt in the hair and scalp. Just think, for example, of the pro-inflammatory and vasoconstrictor action of nicotine and other substances present in cigarette smoke; all this results in an increased production of free radicals, in a lower oxygenation and in a lower intake of nutrients to the hair. Not surprisingly, hair smokers tend to be duller and more fragile than non-smokers.
We must not forget that the main cause of "hair loss" in both women and men is androgenetic alopecia. Some studies (but not all) show how tobacco smoke could be associated with increased levels of androgenic hormones, including DHEA, androstenedione, testosterone and di-hydrotestosterone. The latter, also known as DHT, is the hormone most responsible for androgenetic baldness; in particular, higher levels of di-hydrotestosterone are associated with a greater incidence of androgenetic alopecia in predisposed subjects.
A study conducted on a sample of 740 Taiwanese men aged between 40 and 91 years found that in the long run cigarette smoking generally tends to worsen androgenetic alopecia. In fact, smokers had an approximately two-fold increased risk of moderate or severe androgenetic alopecia (Norwood type = IV) compared to non-smokers.
Cigarette smoking therefore has a negative effect on hair and increases the likelihood of baldness in predisposed subjects. Technically speaking, however, rather than hair loss it is correct to speak of miniaturization of the bulb (structure responsible for the synthesis of the cells that will make up the hair). In the androgenetic alopecia, in fact, the bulb becomes smaller and more superficial, giving rise to a hair thinner, shorter and partly depigmented.