Firstly, blisters - how are those pesky little things formed: 

Blisters are usually caused by friction between your skin and your socks. If there is excessive moisture due to sweaty feet or wet conditions, your skin could also be more susceptible. 

Then, of course, shoe fit is also crucial: Wearing running shoes that are too small or tied way too tightly might also lead to increased friction. At the same time shoes that have too loose-fitting could also cause blisters.

Now, regardless of causes, most runners have at some time suffered from blisters. So, it is good to be armed with some knowledge... Should you pop it or not?

Theories differ, but the general consensus is that if you’ve done a marathon or a very long training session and you’ve got blisters, but you’re not going to run again for at least a week, just leave it to heal. 

But, if you are planning on running again soon, firstly diagnose the cause and remedy that. Then, pop your blister. Graphic, we know, but bear with us here. If you do nothing, the blister might just get worse. So carefully lance it in two areas so it creates a drain. Let the fluid drain and then use an alcohol swab or disinfectant to clean it. Cover it with a specific blister patch and off you go.