I have often found that when I have a sore throat, my speech immediately becomes much worse. Bearing in mind that I believe that stuttering is caused by stress-sensitive vocal cords, I'm wondering if a sore throat can affect our vulnerable vocal cords.
If the vocal cords are indeed the source of our disorder, it would make sense that inflamed vocal cord muscles further reduce the vocal cords' ability to function normally. On the other hand it could also be that other factors which may accompany a sore throat (eg. a fever) impact on general stress levels which could in turn increase vocal cord tension. Then again, don't forget the possible effect of distraction - a sore throat may act as a distraction, thereby actually IMPROVING fluency temporarily ....
This could be an interesting research topic for clinicians interested in the cause of stuttering ...
Update August 2013: A person in the Stuttering Arena Facebook page mentioned that increased stuttering when having a cold or flu probably happens because airflow when speaking is reduced or interfered with due to the nasal cavities being blocked (the "blocked-up" feeling when you have a cold). That makes a lot of sense.
Results of my informal survey in 2011:
In an informal survey on this blog in 2011 I asked: "Is your speech worse when you have a sore throat?" 30 respondents took part, and the results were as follows:
13 respondents (33%) answered "Definitely"
8 respondents (20%) answered "No, I am more fluent"
18 respondents (46%) answered "Haven't noticed a difference"
New poll started 30 December 2012 - kindly participate - many thanks in advance: