Suffocating in 5th edition

This blog isn’t about how I am litterally drowning in 5th edition books, as I prepare sessions for my weekly group or write new content for the DM’s Guild, although it very well could be. No, this is the first in a series of blogs where I go over some of the rules of 5th edition D&D, and give ideas on how to improve (or at least change) them, to inject more realism and tension into your D&D game. Well, let’s not waste words:


When deciding what happens when a character is deprived of breathable air, the Player’s Handbook prescribes that:

A creature can hold its breath for a number of minutes equal to 1 + its Constitution modifier (minimum of 30 seconds). When a creature runs out of breath, it can survive for a number of rounds equal to its Constitution modifier (minimum 1 round). At the start of its next turn, it drops to 0 hit points and is dying.

These rules have one thing overwhelmingly in their favor, which is very much at the core of 5th edition game design: simplicity. Unfortunately, this simplicity comes at the cost of two other very important things.

First off, these rules are not exactly realistic. As for total time, it isn’t too far off. An above-average healthy person (12 Constitution) would do 2 minutes and a few seconds with these rules – which in my opinion is a bit high, but not unbelievable at all. Likewise, an unhealthy person (8 Constitution) would do 36 seconds, which seems fair, and an enormeously healthy person (2o Constitution) would do 6½ minutes, which is still quite shy of the 22 minutes world record.

The problem lies not with the total time, but with the fact that no consideration is made for what you are doing, while trying to hold your breath. You don’t have to be too much of a scientist to know that swimming quick laps or having swordfights might make you run out of oxygen faster than lying calmly at the bottom of a pool.

This becomes the crux of the second problem: suffocation is a very small threat in actual play, at least as a tool for building tension during a combat encounter. Most encounters last less than 10 rounds, and I would say that non-boss encounters probably average around 3-5 rounds. To short a time for even the wizard who dumped his Constitution score to feel particularly threatened. Sure, you can conjure up situations where suffocation comes into play, but it’s very likely to be in a non-combat situation, and that might diffuse the tension a bit.

So, we want a set of rules that can both enhance realism, especially in regards to underwater (or anywhere else you might be oxygen-deprived) activities, as well as something that can build tension during an encounter.

The New Rules

I propose the following rules for suffocation:

  • You have ‘breath points’ equal to your Constitution modifier x 10 (minimum of 5).
  • At the start of your turn, you lose 1 breath point if you don’t have access to air, or regain an amount of breath points equal to 5 + your Constitution modifier if you have access to air.
  • Each time you take an action, bonus action or reaction, you lose 1 breath point.
  • When you suffer a critical hit, you must make a Constitution saving throw to keep holding your breath. The DC equals 10 or half the damage you take, whichever is higher. If you fail, you lose all your breath points.
  • When you would lose a breath point, but have 0 breath points, you must succeed on a DC 10 Constitution saving throw or drop to 0 hit points and start dying at the start of your next turn. The DC of this saving throw increases by 1 each consecutive time it is made without access to breathable air.

Okay, let’s examine these rules.

First off, characters that don’t have a negative Constitution modifier have a full minute of breathing time less. This may or may not be more realistic, but it certainly helps in making suffocation a factor during a combat encounter.

Secondly, dashing, fighting, casting spells and all that jazz decreases the amount of time you have left before you suffocate. This is certainly more realistic. Additionally, going to the surface for a quick breath of air will replenish some, but not all, of your expended oxygen.

Third, a critical hit might very well ruin your day. This puts some excitement into that underwater fight, because any blow can be the one that knocks the air out of your lungs, and now you’re really in trouble.

Fourth, more variance is created with continually forcing Constitution saving throws that increase in DC the longer they go on. A character can potentially keep their breath for whole extra minutes with a good Constitution saving throw. This means that the cap of 6½ minutes becomes anywhere between 5 minutes and (realistically) about 7 or 8 minutes. While this means your character can suddenly run out of air when doing something, or simply starting its turn, you don’t fall unconscious until the start of your next turn, which gives you a round of free-spending of breath points in that frantic break for the surface.

Using the new rules

Breath points are like hit points, except that you don’t measure or keep track of them, until you need to. So the second a character jumps into that pool, or is trapped in that air-sealed chamber, or the magical garrote closes around her neck, write down the character’s breath points next to their hit points, and begin counting down as they start turns and take actions, bonus actions or reactions. If you trust them, encourage your players to tally their own breath points.


Bob the Barbarian has a Constitution modifier of +2. So when the dungeon is flooded, he starts with 20 breath points (2 minutes of air). He must preserve his oxygen, while fighting the kuo-toa that have captured his friend, so that they can both escape.

Round 1. At the start of his first turn, Bob loses 1 breath point. He then rages as a bonus action and makes an attack, losing 2 additional breath points in the process. Bob is at 17 breath points.

Round 2-6. On his following turns, knowing that he should really preserve his breath, he doesn’t spend his bonus action, but only moves and attacks, losing a total of 2 breath points each round. He also makes a single opportunity attack after one of the rounds, so at the end of round 6, Bob is at 6 breath points.

Round 7. Seeing that his companion is drowning, Bob picks up the pace. He loses 1 breath point at the start of his turn, then dashes in, attacks the kuo-toa priestess and makes a frenzy attack as a bonus action. Bob is at 2 breath points by the end of his turn.

Round 8. Bob loses 1 breath point, and now has only 1 left. The situation is dire. Knowing that he won’t be able to defeat the remaining kuo-toa, Bob instead grabs his unconscious friend as an action, and thus loses his last breath point. He starts for the surface.

Round 9 and onwards. With the surface still a 100 feet above him, kuo-toa closing in, and his dying friend in his arms, Bob must now break for the surface before he fails a Constitution saving throw. That’s tension.

Closing Thoughts

All in all, these rules are obviously more complex than the standard ones, but I feel they bring a lot to the table, in the right circumstance. Suffocation happens pretty rarely, and it’s very rare that it needs to be an actual issue how long a character can hold its breath, even with these rules. But for that one special encounter, these rules can really elevate the tension and excitement, creating memorable scenarios and epic last-second-escapes.

I’ve recently published an adventure for Storm King’s Thunder called Kraken’s Gamble, where these rules for suffocation make an appearance in the final battle. If you’re DM’ing Storm King’s Thunder, it might be something for you.

Either way, if you have any comments, criticisms or cool ideas, be sure to leave a comment below, and happy playing!

1 thought on “Suffocating in 5th edition”

  1. I like the reasoning here and overall it’s not too complex and as you point out, rarely used. A few mods to consider:
    – Make breath points equal to 10x your constitution save modifier, this gives extra weight to characters with proficiency in constitution saves, which seems appropriate to me.
    – Make movement cost a breadth point. Means that a character that moves, takes an action, takes a bonus action, and a reaction loses 5 points a round.
    – Make the number of points you regain by being able to breadth proportional to your total number of points say half if you expend your action or 25% if you expend a bonus action.
    – You should also lose breadth points every time you take damage, not just on critical hits. Make it half the total damage taken or similar.

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