In any case, just let the practitioner know this happened so they can assess and act accordingly.
I have personally seen acupuncture to only have the effect of decreasing blood pressure and this is a well reported outcome. However, if your friend was anxious about needling, it might have been a sympathetic nervous response to the treatment, or an unknown mechanism operating within your friend, or something else entirely.
It's difficult to say much more than this because I don't know what your friend was being treated for, what the practitioner's assessment was, what acupuncture points were used or whether or not your friend saw a board certified acupuncturist.
The last point is particularly important. Whether we believe it or not and whether we like it or not, acupuncture has systemic effects. Providers who are not fully trained in the system have no way to predict whether or not those effects might occur and, if they do, how to mitigate them. Unfortunately, at the moment, there are a lot of providers out there who are trying to cash in on acupuncture - they take a weekend seminar and then offer services. This isn't nearly enough training, especially when compared to the thousands of hours a board certified acupuncturist typically has.
All that being said, I have two suggestions for your friend:
1. Make sure they're seeing an NCCAOM board certified acupuncturist.
2. Talk to their provider about what happened after the acupuncture session. Sometimes these events can be diagnostic and might provide that last clue the provider needs to be able to adjust the points used and get better results.