How to get rid of swelling on cold sore due to garlic?

Confusing question: I can't tell what you're asking. Garlic doesn't cause oral herpes oubreaks (cold sores). It also does not treat herpes, and probably would not cause swelling. By far the best treatment for oral herpes outbreaks is valacyclovir (Valtrex®) by mouth. No other treatments work very well. If you have oral herpes, see your doctor for professional advice. Good luck!