Does infect damage dealt to players add poison counters instead of reducing life total?

Infect is a keyword ability defined in CR 702.90. It changes the way damage is dealt both to creatures and to players. When a source with infect deals damage to a player, that damage does not reduce the player's life total at all — instead, the player gets that many poison counters (CR 702.90b).

A player who accumulates 10 or more poison counters loses the game (CR 104.3b). This means an infect source can win the game through an entirely separate damage track, bypassing life totals entirely. The damage is still considered 'damage' for all other purposes (triggering abilities, etc.), it just has a different consequence.

When a source with infect deals damage to a creature, the rules work differently: instead of marking damage normally, the creature gets that many -1/-1 counters (CR 702.90a). So infect changes the damage output for both players and creatures, but in different ways.

Concrete example: Your opponent controls a 3/3 creature with infect and attacks you. If it deals 3 combat damage to you (as a player), your life total stays exactly the same, but you receive 3 poison counters. If you already had 7 poison counters, you now have 10 and immediately lose the game — regardless of your life total.

Note that poison counters gained from infect damage cannot be removed by most effects; only cards that specifically say 'remove poison counters' can do so. Life gain does not offset poison counters in any way.