What are the side effects of dry powder inhaler?

It depends: What kind of medication is it? There are various side effects to different medications. One commonly seen side effect of "dry inhalers" containing steroids is fungal/candida infection of the mouth.

Feeling like: inhaling a dry powder. Number one side effect is discomfort from the powder. Generally it is tolerable. ALso, if it has a steroid, the immunosupression of it can lead to yeast infection of the mouth/tongue/throat. They say to rinse out after using the inhaler to prevent this. other effects can happen rarely, unpredictably and cannot be ruled out as coincedence.

Usually minor: Dry powder inhalers usually have few side effects. The particles can collect in your mouth giving you a bad taste in your mouth. If you swallow the medication it can cause an upset stomach. If there is a steroid in your inhaler you may develop thrush (yeast) in your mouth. If you rinse your mouth with water after use you can avoid these side effects. Good luck.