My experience was that they start very slowly and increase intensity over time and trying to avoid burning! You also need to moisturise. It worked very well and is the best treatment I've used through the national health.

I have just finished the couple of months of narrow and up therapy and my skin has completely cleared up and has been free for about 2 months now! For the first few treatments it will be like you have an intense sunburn on your body making it hard to sleep a little but nothing too bad and definitely worth the results that I have got! But obviously doesn't work for everybody!