What happens when Blood Echo is activated?

Solution 1:

Before I can answer this question, note that there are two different types of Exhaustion effects:

• Timed effects
  • These are caused by the survivor Sprint Burst; Balanced Landing; Lithe; Dead Hard; and Adrenaline perks, Huntress's Toxin addons, Clown's Solvent Jug addon, and the killer Blood Echo perk
• Permanent effects until a condition is resolved
  • These are caused by the Doctor's "Obedience" addon, Doctor's Iridescent King addon, Pig's Slow-Release Toxin addon, Demogorgon's Lifeguard Whistle addon, and the killer Mindbreaker perk

As far as I can tell, these two types are tracked separately.

If you have a timed Exhaustion effect and would gain another timed Exhaustion effect, you will keep whichever timer is longer.