Barry Reay in Aeon:
The anonymous author of the pamphlet Onania (1716) was very worried about masturbation. The ‘shameful vice’, the ‘solitary act of pleasure’, was something too terrible to even be described. The writer agreed with those ‘who are of the opinion, that… it never ought to be spoken of, or hinted at, because the bare mentioning of it may be dangerous to some’. There was, however, little reticence in cataloguing ‘the frightful consequences of self-pollution’. Gonorrhoea, fits, epilepsy, consumption, impotence, headaches, weakness of intellect, backache, pimples, blisters, glandular swelling, trembling, dizziness, heart palpitations, urinary discharge, ‘wandering pains’, and incontinence – were all attributed to the scourge of onanism.
The fear was not confined to men. The full title of the pamphlet wasOnania: Or the Heinous Sin of Self-Pollution, and all its Frightful Consequences (in Both Sexes). Its author was aware that the sin of Onan referred to the spilling of male seed (and divine retribution for the act) but reiterated that he treated ‘of this crime in relation to women as well as men’. ‘[W]hilst the offence is Self-Pollution in both, I could not think of any other word which would so well put the reader in mind both of the sin and its punishment’. Women who indulged could expect disease of the womb, hysteria, infertility and deflowering (the loss of ‘that valuable badge of their chastity and innocence’).
Another bestselling pamphlet was published later in the century:L’onanisme (1760) by Samuel Auguste Tissot. He was critical of Onania, ‘a real chaos … all the author’s reflections are nothing but theological and moral puerilities’, but nevertheless listed ‘the ills of which the English patients complain’.
More here.