How Long Does It Take for Color to Come Back After IPL? (photo)

The face, neck, chest and hands do respond very well to IPL when performed at the correct settings for your skin type. 

 

In contrast, the arms are very special and require lower settings for your first treatment. There are unfortunately alot of pictures similiar or worse than yours on the internet...bars of white that can last for months. 

 

The good news the pigment does typically return and your arms will look normal again. 

 

Do stay out of the sun.

Don't have any additional treatments of IPL, peels, or anything else that can cause inflammation like retin A or hydroquinone.

 

Be a patient patient.

It is difficult to say how long it will take the color to return to normal, but typically I would say 2-3 months. Make sure you are going to a medically-supervised clinic for your IPL or laser treatments to minimize this risk of discoloration and more importantly burns.

Although IPL can be done successfully on the arms, that area can be tricky.  The best way to approach treating pigmentation on the arms, shoulders is to 1) pretreat with a glycolic lotion,  2) have your clinician perform 2-3 chemical peels in the area to reduce excess pigment and break it up.  Then a series of  IPL can be done carefully (using a longer wavelength) and meticulously (as seen in the picture, the lightguide was turned every direction, with gaps between) to finish up the process.  This technique will result in an even, favorable result.  Also, I'm not sure if you were intimating that there were scabs after the treatment, but this is not the desired end point.  My suggestion is to let that skin heal fully, at least 3 weeks, then have your doctor or his/her clinician treat as recommended above to even out that skin.  It will take some time, but I am confident if done correctly, you should not have an undesireable outcome.  Good luck! 

As you are obviously aware, IPL to the arms is very different than the face. One has to be very conservative in this area in terms of the settings. A longer wavelength and lower energy need to be used and treatments should be started conservatively and gradually increased depending on the response. It's alway better to under treat than over treat.
That being said, your arms should return to normal after a few months. I don't have personal experience dealing with this in my patients, but after a few weeks when things have settled down, a very light treatment may be helpful to even out some of the areas of normal pigmentation so they are not as contrasting to the areas of hypo pigmentation. This should obviously be done very carefully so you should talk to your provider to see if they are comfortable with this.
Good luck!