I know that changes to Constitution retroactively affect Maximum Hit Points, but I'm not sure what to do about current hit points.

Say a level 3 character has 12/20 hit points and their Con modifier increases by 1. It makes sense that their maximum HP increases by their level (3) from 20 to 23, but do their current hit points also increase by 3?

In this post (What happens to HP when Constitution decreases?) it looks like the conclusion they came to was that your current HP remained unaffected unless it was above your maximum, in which case it would be reduced to your maximum.

If that is true then keeping logic consistent would suggest that your current HP remains the same when your constitution score increases and that you would have to heal the difference. [In the example with the level 3 character, having their con modifier increase would put them at 12/23 rather than 15/23].

I'm not entirely sure if that is right or not. If Con changes were truly retroactive ("as if you had the new modifier from first level" ~PHB 177) then when the character finished their last long rest they would have been restored to full HP [which in this example is 23/23. Somewhere along the day they take the 8 damage that reduced them to 12/20 originally, but now reduces them to 15/23].

Reading this now, I'm not sure if I should have just asked this on the post I mentioned above. I haven't posted here too many times and I'm not that familiar with how it works.

  • \$\begingroup\$ How, exactly, do you gain constitution score? Amulet of Health? (A process that can be turned off/on again easily might lead to a different ruling for practical reasons) \$\endgroup\$
    – Yakk
    Jul 11, 2022 at 12:42
  • \$\begingroup\$ The obvious one is attuning to an amulet, yeah, or reading a manual. \$\endgroup\$ Jul 11, 2022 at 20:54

2 Answers 2


You don't immediately gain HP

The rules for ability scores includes the following:

If your Constitution modifier changes, your hit point maximum changes as well, as though you had the new modifier from 1st level.

The important part is that it only changes your hit point maximum, not your current hit points which is not mentioned at all. The part saying that it applies as though you had it from level 1 only refers to your maximum HP, not your current HP.

  • 3
    \$\begingroup\$ And yes, it leads to the absurd conclusion that making a character healthier (more CON), also makes them wounded (can benefit from healing effects, i.e. current.HP < max.HP). - - - One can rationalize that by imagining that increasing CON is akin to working out: your body takes a small amount of damage, then gets stronger when it heals. \$\endgroup\$ Jul 11, 2022 at 15:07
  • 1
    \$\begingroup\$ @Mindwin Well, HP are a wierd and almost nonsensical kind of abstraction anyway. Consider if two characters jump off of a tall cliff and falls to the bottom without anything slowing them down. One is a level 1 fighter with high CON - they die on impact. The other is a level 20 wizard with poor CON but enough HP to survive the fall. In what way does that actually make any sense? \$\endgroup\$ Jul 11, 2022 at 21:06
  • \$\begingroup\$ @AllanMills perhaps the wizard has enough experience to lay flat and spread his robes to increase his air resistance, and to tuck and roll to increase the duration of his deceleration at the bottom. Perhaps his fluency in magic results in subconscious micro wards of protection. Much like explanations that incorporate dodging and stamina loss in addition to wounds as part of HP loss during combat, you can stuff any creatively handwavy explanation and flavor you like into the abstraction as long as you don't tie it to any other mechanic. \$\endgroup\$ Jul 12, 2022 at 15:53

Constitution changes only affect maximum hp

Page 15 PHB says:

When your Constitution modifier increases by 1, your hit point maximum increases by 1 for each level you have attained.

Only stating that your maximum changes, not your current hp.

Page 177 PHB has more detail on this:

Your Constitution modifier contributes to your hit points. Typically, you add your Constitution modifier to each Hit Die you roll for your hit points.

To get the additional hit points, you need to spend hit die, upon which they get added to the roll for each die.

If your Constitution modifier changes, your hit point maximum changes as well, as though you had the new modifier from 1st level. For example, if you raise your Constitution score when you reach 4th level and your Constitution modifier increases from +1 to +2, you adjust your hit point maximum as though the modifier had always been +2. So you add 3 hit points for your first three levels, and then roll your hit points for 4th level using your new modifier.

Again, only your hit point maxium increases, retroactively for all levels. The additional hit points in the example are maxiumum hit points, too, within the context of the overall paragraph.

Page 186 PHB, Long Rest:

At the end of a long rest, a character regains all lost hit points.

Technically this might mean you have to take one or more hit die during a long rest to gain the additional maximum hit points as current hit points (as you have not lost them before, you otherwise could not "regain" them). I however do not know anybody who plays it like that: everyone I know plays that you just heal up to hp maxium on long rests.

  • \$\begingroup\$ "Technically this might mean you have to take one or more hit die during a long rest to gain the additional hit points": I am not sure what you are meaning here, are you implying that after a leveling up if you didn't loose HPs but you increased you HP max you have to roll HD to restore all the HPs? \$\endgroup\$
    – Eddymage
    Jul 11, 2022 at 7:52
  • \$\begingroup\$ Eddymage: yes, I think that is because the long rest only says you “regain” hp. And you never lost the added max hp from Con increase. But honestly, I do not know of anyone handling it like this. \$\endgroup\$ Jul 11, 2022 at 8:06
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    \$\begingroup\$ Ok: I would never thought to read that part of the rules in this way, but a very very strict reading seems to suggest your interpretation.. \$\endgroup\$
    – Eddymage
    Jul 11, 2022 at 8:32
  • \$\begingroup\$ Technically it says you regain all lost hitpoints - not just those that haven't previously been regained..... \$\endgroup\$
    – mjt
    Jul 12, 2022 at 14:48
  • \$\begingroup\$ RAI must be "regains all hit points up to maximum" rather than "all lost hit points", because RAW would give you hit points above your maximum in the case of having lost HP due to a constitution score decrease. \$\endgroup\$ Jul 12, 2022 at 15:58

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