The question should be "How bad will it scar?". This ultimately depends on the piercing. Horizontal labrets will scar much less than a bridge piercing because your lips just tend to heal much faster.
I don't claim to know everything about scarring and piercings, however I learned from taking care of my own how to minimize scars visibility. - Take into consideration that there are also different kinds of piercing scarring.
First: Identifying Types Of Scars
Normal Scarring: A scar is simply defined as “a mark left on the skin after the healing of a cut, burn, or other area of wounded tissue,” so scar formation is a normal process following any type of breach in the tissue, including piercing. Unfortunately, however, the body sometimes fails to perform this job properly and complications occur. The most typical types of scars with piercings are just discolored marks, however some of the scarring below is a possibility.
Atrophic Scarring: A depression or pitting below the normal skin level, sometimes occurs when a piercing migrates. Unfortunately, this type of scarring is usually permanent, so there's not much advice I can offer you for how to "make it better". Navel and facial piercings are the most common sites to find this type of pockmark. There are no easy fixes, but a dermatologist can explain treatments such as dermabrasion or laser resurfacing that might be effective. This type of scarring can often look similar to acne scars. If the piercing can be maintained, generally the best way to deal with this problem is to leave jewelry in place. This will usually mask the scar or at least part of it.
Excessive Scarring: The presence of jewelry causes prolonged healing and predisposes the wound to chronic inflammation. Both of these conditions increase the likelihood of excessive scar formation. Keloids and hypertrophic scars are the types of bumps and lumps commonly found on ear cartilage piercings, though other pierced sites also fall victim to these conditions.
A keloid is a very large, dense mound of scar tissue that becomes significantly bigger than your original wound. They can be extremely unsightly, and some grow to shocking dimensions. Unfortunately, once you have formed a keloid, you can seldom fully recover from it and will always have some amount of scar tissue. - Sometimes surgery can help remove these keloids if they become unsightly large.
A hypertrophic scar is a lumpy scar that sits above the surface of the skin. This is the smaller and far more common growth that forms around a piercing. They are not as big or severe as keloids, respond better to treatment, and are more easily resolved. Hypertrophic scarring sometimes goes away spontaneously, or it may recur and recede in cycles for an extended period of time before improving substantially or disappearing.
Hypertrophic scars are frequently mislabeled as keloids—even by doctors—possibly because both are types of excessive scarring. These problems tend to run in families and occur in about 5 to 15 percent of wounds.
1. Cleaning: Always. I mean always keep your piercings clean. Use a mild soap with water or a saline solution. Also be sure to keep all jewelry clean.
2. Coconut Oil: Using coconut oil every night on your piercing - you can use the oil where your piercing was once you take it out, but I recommend doing it ASAP after the removal. For me this has worked extremely well. The moment I began to see slight discoloration when I would take out my vertical labret I began putting this on, and now? No sign of scarring or discoloration - you can't even tell I have it without the jewelry in!
3. Vitamin E: Buy vitamin E capsules from local grocery stores and gently apply to scar area.
4. Mederma: A little pricey, but I used this on a scar on my leg and it seemed to work pretty well!
5. Bio Oil: Though I haven't tried this, I've heard that a lot of people have great results from using it!
All in all, the best way to prevent unsightly scars is to take care of your piercings while they're in.
Out of all the methods, I would recommend the proper cleaning, coconut oil while piercing is still in, and Vitamin E. Oils just seem to seep in a little better and work better - also I'm a little biased because I enjoy the more natural method.