Each type of laser treatment has certain side effects. Below is a list of the 12 most common side effects associated with cosmetic laser use. They may not apply to every single laser procedure and you may not even experience all of these side effects, but the following general side effects are listed for informational purposes:
Post-operative pain is not as big a deal as the pain you experience during the actual laser skin procedure. Topical anesthetics are usually applied to your skin before a cosmetic laser treatment to minimize as much pain as possible. However, you can still feel discomfort after the procedure. For more invasive laser skin treatments, doctors may even prescribe pain pills. It may also be mentally "painful" to wait for your skin to recover.
Redness, swelling, and/or itching
This is a very common side effect of laser skin treatments. Traditional ablative lasers would physically vaporize the top layer of your skin, leaving it red and raw for months until it healed on its own. Non-ablative lasers, while less intensive, claim to have no downtime, but facial redness (erythema), swelling, and even itching are common post-laser side effects. These symptoms will usually subside after a few days, though "pink" skin may linger for many weeks later.
Sensitivity to the sun
Since cosmetic lasers pretty much heat or damage your skin to encourage it to heal, it is no wonder that laser skin treatments will make your skin more sensitive to the sun. After you get laser done on your face, it is extremely important to stay out of the sun during peak hours and wear proper sunscreen protection. You don't want to get any kind of photodamage when your skin is already sensitive.
Changes in skin pigmentation
Not everyone's skin is suitable for laser treatment. Generally, cosmetic lasers work better on people with lighter skin tones than on people with darker skin tones, but both kinds of skin tones have a risk of hypo-pigmentation (lightening of the skin) or hyperpigmentation (darkening of the skin). Asian skin is particularly prone to hyperpigmentation, especially with high strength or deeply penetrating cosmetic lasers. Although some laser skin procedures, such as those that treat pigmented lesions like sun spots, will make the pigmentation spots darker before they get better.
Depending on the type of laser skin treatment, bruising could be one of your side effects. This symptom is more common in pulsed-dye lasers where treated areas can develop purpura, or purple spots in the skin when blood vessels under the skin leak.
A demarcation line represents a change in your skin color where the cosmetic laser was applied and where the laser was not. If this happens, it usually shows up around the eyes, lips, and jaw line of your face. Demarcation occurs when you experience a loss of pigment in your skin from the laser in the treated area compared to the untreated area of your skin. There is not much you can do to treat demarcation lines other than trying to depigment the rest of your skin to match the lighter color, though this is a difficult task. Makeup is usually the best (yet cumbersome and impermanent) solution for demarcation lines.
Infection is not a very common side effect, but it can happen, especially with some of the more invasive cosmetic laser procedures. Most doctors will prescribe antibiotic creams and pills to take post-op to prevent any kind of infection from occurring. If your skin scabs post-laser, you must also resist the urge to pick them off or you will risk infection as well.
It's funny how cosmetic lasers can be used to treat scars yet cause scarring on your skin. Any kind of treatment that "damages your skin to make it better," will carry a risk of scarring. Whether you will scar will largely depend on your type of skin. If you are prone to scarring or getting keloids (raised scars), laser skin treatments might be risky procedures for you to undertake.
Blistering, scabbing and crusting
These are moderate to severe side effects of cosmetic lasers and light-based facial treatments like IPL. Most of the time, you will seem like you have a sunburn post-laser, but sometimes blistering, scabbing, and even crusting can occur on your face. These symptoms must be left alone to heal on their own.
Fat loss, especially facial fat loss, is more common with radiofrequency treatments like Thermage. Because radiofrequency constricts fat cells, many people have experienced a gaunter looking face post-op. There is nothing that can be done to reverse the effects of fat loss short of fat grafting surgery.
Recurrence of the skin issue
It usually takes more than one laser skin treatment to get your desired results. However, even after multiple treatments, some skin conditions will come back. This is more common with cosmetic lasers that treat vascular lesions and remove hair. With broken capillaries, for instance, lasers can destroy the blood vessels, but a laser treatment will not prevent your skin from growing more blood vessels.
Some people experience "purging" or minor breakouts post-op. This could be from the stimulation of your skin by the laser treatment or from the emollient healing creams you apply after the procedure. In general, you should not get laser treatments if you have active acne or irritated skin. While some cosmetic lasers claim to treat acne, it is my belief that lasers best treat acne marks and scars, not active acne itself.
Besides running the risk of having to deal with the above side effects, laser skin procedures are also very expensive. You may end up feeling disappointed after spending thousands of dollars on laser treatments if you don't maintain realistic expectations. Make sure you are a suitable candidate for the type of cosmetic laser in question and take good care of your skin pre and post op. Keep in mind that results may not be immediate either. Even after you recover from the laser treatment, it may still take some time for the full results of the laser to develop as your skin continues to heal and improve.
If you are feeling iffy or hesitant about a certain laser treatment, it's best to hold off until you feel 100% sure that you will not regret the procedure.