Frenzy is optional

Entering Rage does not automatically create exhaustion. The player explicitly chooses whether that Rage becomes a Frenzy.

The extra attack starts after the opening turn

The bonus-action melee weapon attack is available on each of your turns after the turn on which the Frenzy starts.

Exhaustion arrives when the Rage ends

The drawback is delayed until the Frenzied Rage ends, so the penalty does not reduce the current Frenzy's output before it finishes.

Repeated Frenzies accumulate exhaustion

Using Frenzy repeatedly without removing exhaustion can create increasingly serious penalties under the campaign's 2014 exhaustion rules.

2014 versus 2024 Berserker

The 2024 Berserker rewrites Frenzy substantially. The rules below therefore use the 2014 exhaustion-based Berserker, matching the 2014 Barbarian ruleset.