Are there any consequences for Dashing every round?

Question

Can I use the Dash action every round without becoming exhausted? Do I become exhausted if I move 60 feet every round with Dash?

Answer 1

You can Dash every round freely, unless your DM says otherwise

Despite the Player's Handbook says nothing about that explicitly, your DM might decide that running exhausts you, using additional mechanics from the Dungeon Master's Guide. See DMG page 252, "Chases":

During the chase, a participant can freely use the Dash action a number of times equal to 3 + its Constitution modifier. Each additional Dash action it takes during the chase requires the creature to succeed on a DC 10 Constitution check at the end of its turn or gain one level of exhaustion.

As the DMG suggests, when you chase (or run away from) someone, you can move 60 feet 3+CON times without problems, then you have to make a CON check or get one level of exhaustion. DMG assumes these rules for chases, but nothing prevents your DM from use them in combat as well, if they thinks it's reasonable.

However, exhaustion levels gained during the chase are not "real" ones — they all can be removed by finishing a single short rest:

A participant drops out of the chase if its exhaustion reaches level 5, since its speed becomes 0. A creature can remove the levels of exhaustion it gained during the chase by finishing a short or long rest.

Answer 2

Can I use the Dash action every round without any consequences?

By a strict application of the movement rules, yes. The DMG introduced Chase rules that allows the DM to change this, adding a random element into it.

It's up to the DM. RAW, there is the chase rules for chases, which state that:

During the chase, a participant can freely use the Dash action a number of times equal to 3 + its Constitution modifier. Each additional Dash action it takes during the chase requires the creature to succeed on a DC 10 Constitution check at the end of its turn or gain one level of exhaustion.

A participant drops out of the chase if its exhaustion reaches level 5, since its speed becomes 0. A creature can remove the levels of exhaustion it gained during the chase by finishing a short or long rest. (DMG 252)

Of course, this isn't required for combat encounters to be used and isn't even required to be used for chases (although it makes chases much more fun, in my opinion).

From a DM perspective, I would opt to use the chase rules unless there wasn't a good reason to. I find that players don't seem to take the Dash action very often anyway.

Do I become exhausted if I move 60 feet every round with Dash?

It's up to DM discretion, but using the chase rules:

1. Is this the 3 + Con Mod's time using Dash? If not, no.
2. Does the creature pass a DC 10 Constitution ability check? If so, no. If not, add one level of exhaustion.