Cystic pimples are deep, painful, and stubborn. While it's challenging to completely eliminate them overnight, you can take steps for how to shrink a cystic pimple overnight:

Ice: Apply an ice cube wrapped in a clean cloth for 5-10 minutes to reduce inflammation.
Spot Treatment: Use an over-the-counter or prescription acne treatment with benzoyl peroxide or salicylic acid.
Warm Compress: After icing, use a warm, damp cloth to encourage drainage.
Avoid Picking: Don't squeeze or pick the pimple, as it can worsen inflammation and lead to scarring.
Overnight Patches: Some hydrocolloid patches can help absorb excess fluid and reduce swelling.
Consult a Dermatologist: If cystic acne is persistent, consult a dermatologist for professional treatment.