I'm a 23 year old guy and very timid as well...been like this my entire life. However, there is some hope and you can improve somewhat. I believe you won't be fully able to alter your personality, but you can definitely modify certain aspects of it. I certainly have over the first year of pharmacy school. Once you're in professional school, being a little more outspoken will come more naturally to you, as it will be required during IPPE/rotations and in communication with your peers. Also, when you enter pharmacy school and realize everyone else is extroverted and making friends more easily and you're staying behind, you will in one way or another speak up a bit more and make some friends of your own; hence, your shyness will diminish somewhat.
That's what happened to me. I'm about to be a P2 and I've made more friends in pharmacy school than I've ever had in all my education. However, as a result of my shyness and overall personality, I find that I associate much more effectively with older individuals...mostly people in their late 20s and in their 30s and don't share much in common with youth my age. However, all of this is still part of the survival process. I'm going out-of-state to school and no longer live with my parents. I'm on my own and I'm practically forced into opening up a bit more or risk isolation. Additionally, if you're an overachiever and have a very strong foundation from what you're learning in school, you will excel as an intern when it comes to consulting with patients under the pharmacist's supervision. I find that if I really know what I'm talking about and feel 100% confidence in what I'm discussing or explaining, I lose all inhibitions. So, you will feel great consulting with patients even if you're shy once you realize you know your stuff and can convey the information to the public. I'm going to start my IPPE intern hours during second year, but I know I will thrive when it comes to this type of stuff. Now, if you ask me about chit chat/small talk, I'm out...
The point is, you don't have much to worry about. You will adapt as needed whether you want to or not. 👍