Can You Play Hearts on the First Trick?

Short Answer
No. In standard Hearts rules, penalty cards (Hearts and the Queen of Spades) cannot be played on the first trick. The first trick starts with the player holding the 2 of Clubs, and all players must follow suit if possible.

Why This Rule Exists

The first trick restriction serves important gameplay purposes:

Example

The 2♣ is led. You have no clubs but have 5♥, Q♠, and 8♦. You must play the 8♦ because hearts and Q♠ are prohibited on the first trick.

What If You Only Have Hearts?

This is exceptionally rare but can happen. In most rule variants:

Cards You Can Play on First Trick