I use the Crest white strips coupled with sensodyne whitening t/p, every 6 months, no problems

Have you discussed teeth whitening with your dentist? A good option is to have custom whitening trays made by your dentist and then to purchase the bleach to apply to the trays. You have many choices on when/how to wear the trays. A big benefit is that once you have the trays you can whiten a couple of times per year, usually after your cleaning appointments. I am currently whitening my teeth and it only takes a few nights of wearing the trays to see dramatic improvement. I am a dental hygienist and have seen every option available. The custom trays are the best, IMO.

I had custom trays made a number of years ago and continue to use them, so consider them a good investment. They, along with the whitening agent purchased from my dentist at about $40 for two vials, do a far superior job over the OTC strips or pens. I would highly recommend you discuss options with your dentist.

I did custom trays a few years ago but unfortunately the bleaching solution, even the weakest one, made my gums so sensitive and painful I couldn't continue. My dentist said some people just can't go that route. If you do, definitely use Sensodyne toothpaste just in case.

I have trays and buy the bleach on Amazon. It is far less expensive there than from the dentist and is exactly the same thing. One time I bought the 35 percent bleach which was so strong it bleached my gums! Whata sight. The color came back in half an hour or so but I sure was worried that I was going to have to walk around with white gums. Now I use the Opalescence 20 percent. I just checked on Amazon and they do sell a variety of teeth bleaching pens, so try looking there.

A lot of people can't sleep with those bleaching trays or Invisalign trays

True, they can be annoying. I am only supposed to wear mine for half an hour at a time, every day for two weeks. I use it after I have had my teeth cleaned, but only for a few days.