I think one consequence of early Viagra is a much more aggressive AIDS epidemic.
Gay meeting places in OTL sometimes have bowls full of Viagra to counteract effects of stay-awake-all-night drugs such as Meth. But condoms are common, too. Now, anyway.
In this TL, gay bathhouses and other meeting places are still unaware of the danger. With Viagra, a man could go all night in his activities ... and the epidemic that will become a household name in just 2 years would be so far gone, hundreds of thousands, instead of just tens of thousands, of people would have died in the US alone.
Another consequence: As a result of the connection between Viagra and AIDS made later on, Viagra is no longer available.