“Can being addicted to porn cause me any harm?”

Any addiction results in cumulative harm. The porn addiction may have a negative impact on the mind and behavior of the person. On one side, it may over-sexualize his relationships impairing the capacity to have deeper knowledge and real emotional intimacy with himself and with others. If he has a relationship this may result in cycles of extreme behavior change of excessive pressure for sexual activities or lack of sexual interest with the partner. In cases of people with other mental disorders, it may complicate with the gradual introduction of risky sexual behaviors with multiple persons or even to behaviors that violate the law. Any addiction results in the loss of natural human values and creative behaviors that are gradually changed with automatic stereotyped behaviors: to get immediate pleasure behaviors or to immediate pain escape. That may probably result in a deterioration of our self esteem and self help abilities and to the stagnation in our development as human beings to our full potential. There are several professionals that offer help for sexual addiction, but I recommend to be careful in selecting a real mental health professional with good recommendations.
Thanks.

If it is interfering in your activities of daily living yes. If you are viewing illegal acts yes. Seeking a therapist versed in this area would be very helpful.