In A Midsummer Night's Dream, the antidote for the love potion is provided by -Oberon -Hippolyta -Helena -Puck mustardseed

Actually, there is no 'antidote' to the love potion that
Oberon gives Puck to use on the Athenian lovers and Titania. What Puck does to sort out
the chaos of the situation between the Athenian lovers is that he annoints the eyes of
the lovers again and makes sure that when they wake up the first person they will see is
the person that they should be with. Note Puck's words at the end of Act
III:

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When thou
wakest,
Thou takest
True
delight
In the sight
Of thy
former lady's eye:
And the country proverb
known,
That every man should take his
own,
In your waking shall be
shown:
Jack shall have
Jill;
Nought shall go ill;
The
man shall have his mare again, and all shall be
well.

So it is that
Puck is the character that resolves the hilarious chaos that has caused the Athenian
lovers to love each other in hilarious combinations, but it is not an 'antidote' as your
question puts it. Rather the magic is used effectively to bring about the happy ending
that Oberon desired.