I would stop the conversation and give him the floor, making it clear that this way he can express everything he needs to comment on, and then allow me to speak without interrupting me. So that I can also present my point of view fluently without him losing the ideas of what he wants to comment on. Along the same lines, I would suggest that next time he write down the ideas he wants to share and do so at the end of the conversation so that it can be more effective for everyone.

To regain control of a conversation with a coworker who constantly interrupts, maintain confident body language and speak clearly, signaling that you are still speaking. Politely ask to finish your thought before they respond, using phrases like, "Let me finish, and then I’ll hear you out." If the interruptions persist, consider addressing the issue directly in a private conversation, suggesting that both of you allow space to finish thoughts for more productive communication. This approach sets respectful boundaries and ensures your message is heard.

When facing frequent interruptions from a coworker, I wouldn’t aim to “regain control” but rather to ensure the conversation remains productive and collaborative. I would introduce a “talking chip” method, a strategy often used in classrooms, where each participant would have a turn to share their points fully within a set time; before the next person speaks. Additionally, I would suggest note-taking to capture and revisit my thoughts without interrupting. While I respect the coworker’s enthusiasm, setting boundaries with these approaches would foster respectful dialogue, keeping the discussion structured, and ensure that ideas are heard and valued.

You can let them finish everything that they have to say and wait for the right moment to put in your thoughts respectfully in the conversation. Make sure you write down the points that are getting discussed so you can later pick and talk about each or some of the points that you wanted to discuss or wanted to add your own insights.