A syringe with a red substance in it.
Isaac becomes pale with signs of sickness on his body, and gets bumps and markings.
Touching enemies will inflict them with poison, as well as deal a large amount of damage.
- Book Of Shadows - Turns you invincible with the poison touch effect still working while invincible.
- The Polaroid - While invincible, allows Isaac to poison enemies without taking damage.
- Celtic Cross - If invincibility triggers, poison touch will be effective against many enemies.
- My Little Unicorn/The Gamekid - Poison touch overrides their 40 damage hit with its 30 damage hit (and poison). Otherwise it doesn't change what they do.
- The Nail - The contact damage of The Virus overrides the contact damage of The Nail.
- Mom's Bra/Mom's Pad - Contact damage on the player is disabled during the effect of either active. This allowing for safer application of the contact damage and poison damage of The Virus.
- Best Friend - The brief window of invincibility frames when casting Best Friend allow for a free application of The Virus.
- The substance in the syringe is probably infected blood, which is an incredibly easy way to contract STDs.
- Lust is a recolor of Isaac with The Virus graphic applied. Lust also has a chance to drop The Virus upon death.
- This may be why it's thought to be an STD.
- The Virus, like all other contact damage items, cannot inflict contact damage or poison damage to Hearts or Mom's Heart/It Lives, but can do so to other enemies that don't deal contact damage to the player.