I've been suffering from cold sores for manu years. Some remedies that i find useful are:
Tea tree oil + coconut oil
Powder used for heat rash (prickly heat rash) some powders work better than others. Try different brands.
And the real quick way
ANY WHITE TOOTHPASTE
bonus points if its with mint.
Dab it on first sign of tingling and it won't develop into blister.keep using it until tingling sensation goes away.
Hope it helps.))))