Herpes (cold sores) is caused by a virus and usually cannot be completely cleared overnight because it requires a specific healing process.

The most important trick for a quick cure is to act immediately at the very first signs (tingling, itching, or tightness):

The Most Effective Trick: Early Application
Antiviral Cream (pharmacy): Apply a cream with antiviral agents such as acyclovir or penciclovir.
The key: The sooner you apply the cream (ideally at the first tingling sensation), the better it can stop the virus from multiplying and prevent or significantly shorten a full-blown outbreak.
Application: Apply consistently every few hours, as directed in the package insert (often 5 times daily), with a fresh cotton swab.

Cold sore patches: These discreet plasters often contain hydrocolloid, cover the area, keep the wound moist (which promotes faster healing without scab formation), and prevent the spread of viruses.
Additional tips for overnight support:
If you’ve already used the antiviral cream or patch, you can further support the healing process:

Icing: In the first few hours, when the tingling sensation begins, place a cold pack or ice wrapped in a cloth on the area. The cold can reduce inflammation and slow viral replication. (Caution: Do not apply directly to the skin!)

Home remedies for drying: If the blisters are already oozing, zinc ointment or Manuka honey can help.
Zinc ointment: Has a drying and anti-inflammatory effect.
Honey (especially Manuka honey): Is said to have antibacterial and wound-healing properties.
Important: Avoid touching or scratching the blisters, as the fluid is highly contagious and the viruses can be transmitted to other areas (e.g., the eyes or hands) or to other people.