Constitution Mod to HP

[Rhaen]

Hello All!

I had a quick question about how the rules interpret your Constitution HP mod when your Constitution mod changes. Does your Constitution HP mod change the amount of HP you get per level if your mod changes for any reason?

For example:

Level 3 Bard (Favored Class)
Str 6 (-2), Dex 14 (+2), Con 9 (-1), Int 12 (+1), Wis 11 (0), Cha 16 (+3)

Level 1 HP: 8 (Full HD) + (-1) (Const Mod) + 1 (Favored Class Bonus) = 8
Level 2 HP: 8 (Level 1 HP) + 1d8 Roll (5 Average) + (-1) (Const Mod) + 1 (Favored Class Bonus) = 13
Level 3 HP: 13 (Level 2 HP) + 1d8 Roll (5 Average) + (-1) (Const Mod) + 1 (Favored Class Bonus) = 18

When the Bard above hits 4th level and he/she chooses to take their ability score increase in Constitution (changing the modifier from -1 to 0), are the previous level Constitution mods affected or is it only future mods? The former would mean that a pretty substantial HP increase occurs at 4th level but the latter seems to make more sense to me.

Just an FYI, the reason I am asking is because I am using Hero Lab to add a character and it applies the new mod to all levels and not just the new ones and I wanted to know if this was the way the rules are interpreted or if it is a calculation issue on Hero Lab's part.

Thanks!

[Wu Nakitu]

Hero Lab is correct in this case; a permanent change to your Con mod applies going forward and retroactively.

[MeanMutton]

Wu is correct. Here's the relevant rule:

Permanent Bonuses wrote:

Ability bonuses with a duration greater than 1 day actually increase the relevant ability score after 24 hours. Modify all skills and statistics as appropriate. This might cause you to gain skill points, hit points, and other bonuses. These bonuses should be noted separately in case they are removed.

[Rhaen]

Thanks for the clarification, Wu and Mean.

This is very helpful.

[Imbicatus]

Temporary changes to con apply this way as well, such as a Barbarian Rage.

[Ciaran Barnes]

Also make sure to lower your hit points if you suffer constitution damage or drain.

[Rhaen]

Ciaran Barnes wrote:

Also make sure to lower your hit points if you suffer constitution damage or drain.

This is an interesting point... Let's say that you take constitution damage to reduce your mod by 1. At 4th level, you would lose 4 HP from your max HP pool. When your Con damaged is mended, you regain your 4 HP points to your max pool, but do your actual hit points increase with your max pool or must you be healed to max?

My understanding is that if you are at max HP and your pool increases (due to level up or otherwise), your hit points increase with your pool but if you are not at max health, only your pool increases and you must be healed up to your new max pool. Is this correct?

[Brf]

CRB wrote:

Constitution: Temporary increases to your Constitution score give you a bonus on your Fortitude saving throws. In addition, multiply your total Hit Dice by this bonus and add that amount to your current and total hit points. When the bonus ends, remove this total from your current and total hit points.

Constitution: Damage to your Constitution score causes you to take penalties on your Fortitude saving throws. In addition, multiply your total Hit Dice by this penalty and subtract that amount from your current and total hit points. Lost hit points are restored when the damage to your Constitution is healed.

In other words, both your current HP and maximum HP change with constitution changes.

[Rhaen]

Brf wrote:

CRB wrote:

Constitution: Temporary increases to your Constitution score give you a bonus on your Fortitude saving throws. In addition, multiply your total Hit Dice by this bonus and add that amount to your current and total hit points. When the bonus ends, remove this total from your current and total hit points.

Constitution: Damage to your Constitution score causes you to take penalties on your Fortitude saving throws. In addition, multiply your total Hit Dice by this penalty and subtract that amount from your current and total hit points. Lost hit points are restored when the damage to your Constitution is healed.

In other words, both your current HP and maximum HP change with constitution changes.

Of course there is a clear CRB rule on it. Thank you very much!

[Claxon]

Ciaran Barnes wrote:

Also make sure to lower your hit points if you suffer constitution damage or drain.

Only constitution drain actually changes your constitution.

Constitution damage merely applies a penalty to some things that are based off constitution.

Quote:

Constitution: Damage to your Constitution score causes you to take penalties on your Fortitude saving throws. In addition, multiply your total Hit Dice by this penalty and subtract that amount from your current and total hit points. Lost hit points are restored when the damage to your Constitution is healed.

[Jeffrey Fox]

Claxon wrote:

Ciaran Barnes wrote:

Also make sure to lower your hit points if you suffer constitution damage or drain.

Only constitution drain actually changes your constitution.

Constitution damage merely applies a penalty to some things that are based off constitution.

Quote:

Constitution: Damage to your Constitution score causes you to take penalties on your Fortitude saving throws. In addition, multiply your total Hit Dice by this penalty and subtract that amount from your current and total hit points. Lost hit points are restored when the damage to your Constitution is healed.

Correct and one of those things are current and max hit points are lowered based on the penalty inflicted by constitution damage.

[Ciaran Barnes]

One thing about ability damage, you suffer a -1 penalty to your ability modifier per two points of ability damage. What this means is that even if your Constitution is 14 and you get one point of Con damage, you don't lose any hit points yet. If you gain one more point of Con damage (for a total of two), you would subtract your level from your current and maximum number of hit points.