Fever Blisters, also known as cold sores are what Herpes outbreaks are called. The oral form of herpes HSV-1, usually appears on the lips or near them. Fever Blisters are very contagious. As many as 4/5 people carry the Herpes virus. However only 2/5 get recurring outbreaks. Many people carry the virus but have no idea because they have never had an outbreak.
They will usually last a week depending on the severity and how you treat them. If you leave them alone and do not apply any type of medicine (pharmaceutical or natural) they will be very painful and irritating. The best thing you can do is apply medicine at the first stages of an outbreak. This will reduce the amount of swelling, and will not allow the fever blister to spread.
There are many stages of a cold sore outbreak. The first stage is the Inflammation stage where the virus is triggered and begins to replicate. At this point the fever blister will turn red and swell up.
This is the key stage to start applying medicine. If you fail to do this then the cold sore will be difficult to treat.
The weeping stage is when the vesicles are formed which contain the virus. This is the most painful and unsightly stage as the vesicles start to open up and ooze. The next stage is the scab stage. The virus is beginning to retreat and a scab is formed over the open sore. After several days, the healing stage will occur. This is when the scab peels of and the skin underneath is repaired. You may have a red shade where the open sore was for a couple of days.