Days 1–2: The Early Stage
Before any visible symptoms appear, you may feel a tingle, itch and/or burning sensation. This is often called the "Tingle Stage" and may last from a few hours to a day. Usually there is a feeling of the skin tightening in the area where the cold sore is about to develop, before there are any visible signs. The area then becomes red and swollen due to the inflammatory reaction to the infection. The infection is contagious even at this phase, so avoid close physical contact. Start using ABREVA at this stage for best results.

Days 2–4: The Blister Stage
The blister appears. A group of small, painful lumps multiply and/or become enlarged. White blood cells travel to the blister and help fight the infection. The cold sore blister fills with fluid and contains millions of virus particles.

Day 4: The Ulcer Stage
During the ulcer stage (typically the most painful), the blisters will burst and you will notice a shallow ulcer (open sore) develop. A red ring of inflammation around the affected area may also appear. Continue using ABREVA until the ulcer heals.

Days 5–8: The Scabbing Stage
As the cold sore dries out, a golden-brown crust appears and forms a scab. As the scab shrinks, you may experience painful cracks that can bleed. Severe itching and/or burning are also common.

Days 8–10: The Healing Stage
As the cold sore heals and the scab starts to come off, you may experience some dry flaking and residual swelling. The skin may also remain slightly pink or red. This is still a good time to be using ABREVA.