Hehe that was Shane in his prime sometime in the 1980s...even at his best he had the teeth of a goblin .Id say it was as much heavy smoking and drinking as it was anything else. He became addicted to heroin when they threw him out of the band but I believe that was in the early 1990s.

There is a pretty fascinating documentary about his life that came out in 2020 called Crock of Gold - A few rounds with Shane MacGowan. Johnny Depp was the producer or executive producer I believe .

Shanes technically one of if not the most successful musicians of all time in terms of royalties. He earns around £350,000 a year from Fairytale of New York.

I'm surprized he's still alive.

You can find Crock of Gold here, its best watched with a few good whiskies :).
https://www1.freemoviesfull.com/watch-movie/watch-crock-of-gold-a-few-rounds-with-shane-macgowan-66690.5507383