Is There Any Way to Whiten Veneers?

Porcelain veneers are stain resistant and should not change in color.   If it seems like the veneers are getting darker, many times this is a sign the underlying tooth is darkening and other times the space between the veneer and natural tooth is open and perhaps the veneer margins are leaking yielding a darker veneer,  In both of these instances a new veneer(s) is needed to correct the discoloring and integrity of the veneer.

Porcelain veneers will not change color and can't be bleached.  If you feel that they have turned darker you either have leakage underneath the veneers or the natural tooth is turning dark under the veneers.  Either of these caused can only be corrected by replacing the veneers.  Good luck.

You have a few options.
1 A professional dentist can whiten your teeth from behind 
2 whitening strips can remove lighter stains from the front part of the porcelain veneers.
3 We have a special paste that we use to brighten up veneers and give them back their shine, that's usually done at a prophylaxis appointment.
Hope this helps 
Joseph Goodman DDS, Beverly Hills 

I would recommend seeking professional consultation. There is a technique by which you could bleach the back side of the veneers using a custom-made tray designed especially for this purpose. 

Not sure why your "veneers" are getting stained.  You may had gotten the composite type "veneers".  Some dentists will do these plastic white filling bonding veneers and patient believe that they've gotten the porcelain veneers.  I've encountered a ton of patients swore that they had porcelain veneers and in reality what they had gotten plastic cheap composite fillings veneers.  Composite will stain, porcelain does not.  If your "veneers" got stained or is getting darker, then you may have composite veneers.  If you do indeed have a composite veneer, then just have the dentist grind the old filling composite veneer away and place another new composite veneer on.

Dental restorations such as veneers, crowns, and fillings will not whiten. They may accumulate surface stains that can be removed with cleanings but they will not whiten with traditional whitening methods. 

Hi:If there is external staining on your veneers, the best product  to use to whiten them is Oral Essentials Whitening Strips.  It does not contain any peroxide and is safe for porcelain.Best,Dr. Maddahi

Veneers are made of a very nonporous material, unless they are defective, or were adjusted by your dentist chair-side which left them without glaze.
Equally, veneers tend to be very thin, which means there can be a lot of natural tooth tissue behind them that can itself absorb stain and darker over time.
If this process is extensive (if say you smoke or have lots of coffee and staining foods and rarely see the hygienist) then this can have a significant effect on the appearance of your veneer. 
Start with the simplest, cheapest option first - see a hygienist and see if you are happy with the improvement. after that, if the discrepancy remains, you need to see a cosmetic dentist about this problem. 
Good luck with finding a solution!
Kind regards

Thomas Dey, BDS, MSc

Whitening treatments will have no effect on porcelain veneers. If a patient is considering whitening teeth, we will recommend that they finish all bleaching procedures at least 1 month before veneer treatment is performed so that a stable shade can be determined.

Veneers are made out of different types of porcelains, in general porcelain doesn't change color.  you need to find out why your veneers seems darker.  Is it a Root canal teeth that is getting darker and now showing through?  Do you have open margins on your veneers? Are they just stained?  See an experienced cosmetic dentist, to get a correct diagnosis and treatment .