no itching,only small black dots on penis..look like dry
Most males get a reaction to everyday things that the penis is in contact with, in numerical terms, because most males use soap and things like shower gel and other forms of body wash to clean the penis with, then these are the most frequent causes of a skin reaction.
Some sexually active males that use condoms regularly can get a reaction to the condom itself. Less likely, but still a possibility is that you are getting a reaction to whatever your clothes are washed in.
What you need to think about is everything that touches the skin of your penis - I have mentioned soap and things like that, but do you also apply anything else to your penis, such as skin cream or anything like that?
Think about what your penile skin is experiencing on a regular basis? For example, many men masturbate quite frequently - this is a source of major friction for the sensitive skin at the tip of the penis.
Do you have skin problems or reactions anywhere else on your body?
To identify the black dots it would help if you can post a photo / image that clearly shows these to identify what they are …