One of the possible consequences of a root canal is inflammation.
You can find more at my website. See the answer to this question and others about root canals at https://www.atozdentalcare.com/ask-your-dentist/
Some medications cause tissue reactions that you don't want.
Go back to your doctor if it doesn't improve in five days.
Your face is swollen because the cause of the infection (i.e., dead root tissue, decay/bacteria and antibodies all work to form purulent exudate or "pus") has not been completely removed and has liquefied the bone under the tooth. The tooth is under pressure and the pus needs somewhere to exit. The path of least resistance, believe it or not, is oftentimes your bone. After the bone, it gets into your gum tissue and affects the millions of cells there; this swelling of the face is called cellulitis and should be treated immediately.
In my experience, I've also seen this if the offending tooth has a root fracture or has split. Periodontal, or gum abscess, can cause the face to swell, with or without a root canal. Take all prescribed medications that your doctor prescribed and make an appointment asap to see your dentist.
Hope this helps. Good luck!
Hang in there, and don’t exercise or operate heavy machinery. You need to give your body the time it takes to heal!