Day 1-2 (Tingle/Prodrome Stage):
The first symptom that a cold sore is developing is a sense of soreness and tingling at the location the blisters will form. This typically happens 1-2 days prior to the development of the blisters.
Day 2-3 (Blister Stage):
The first visible sign of a cold sore is the appearance of several fluid filled blisters. The blisters are usually very small and may later join together to form one or two larger blisters.
Day 4 (Weeping Stage):
Soon after the fluid filled blisters have formed, they will rupture. This is when cold sores are the most painful and most contagious.
Day 5-7 (Crusting Stage):
The healing cold sores will form scabs on the skin that may itch and burn. The skin may become very dry, causing the skin to crack and bleed.
Day 8-10 (Healing Stage)
The scabs that have formed on the skin will gradually fall off, to be replaced with smaller scabs until the skin has completely healed.