“It always seems like I get acne when I feel myself getting sick, or just before. Is there a connection there, or is it just an unpleasant coincidence?”
I quickly searched the medical literature for clinical studies, but did not identify any that explored the relationship between cold and influenza (flu) viruses and acne outbreaks.
However, it sounds as though you are consistently observing this relationship. While it could just be an unfortunate coincidence, as you say, it is possible that there is an alternate explanation for what you are seeing.
Some viral illnesses can produce an acne-like rash, so that is one possibility. Another consideration is that when we are feeling ‘run down’ our immune systems may not function at full capacity, which makes us more susceptible to viral illnesses.
At the same time, an immune system that is not functioning at full capacity may permit more bacteria to grow on the skin. Bacteria contribute to acne by producing fatty acids, which can block the pores, and causing inflammation. Both of these factors can contribute to the development of acne lesions.
This is just a theory about why you might see a connection between the onset of a viral illness and an acne outbreak. Regardless, when you are starting to feel sick, it might be advisable to pay particular attention to your skin care routine, to try to prevent new acne lesions from developing.