I use an electric toothbrush. I get cold sores frequently. How can I sanitize my toothbrush? At $22 per head I cannot afford to replace each time.

Peridex (chlorhexidine gluconate) Ask your dentist to write a rxn for peridex (chlorhexidine gluconate). It is an antimicrobial mouth rinse. You can rinse your brush head in hot water , then let it soak in this for 15 - 30 minutes, then rinse again and allow to dry. Also, you might invest in 2 brush heads and alternate so they dry completely. Good luck. The cold sores are viral.If herpes, ask your dentist for rxn for acyclivir. Often helps.
Maybe toothpaste? Toothbrushes are abut as sanitary as eating utensils. You cannot "sterilize" a tooth brush. Short of it falling in your toilet, just rinse it off and use a paper towel to remove moisture and let it dry. Your cold sores may be a result of the type of toothpaste you are using. Try one without the foaming action sodium laurel sulfate.
Listerine. Soak it in a little bit of listerine mouthwash. Change the mouthwash daily. Get a new brush head every 3 months.
White vinnegar. Excellent for cleaning dilute. 50/50 with water half hour soak. Rinse copius amounts of water.
See below. Best advise i can give you is to buy some regular toothbrush and use them when you are having an outbreak. Once your soars completely clear than start using your electric toothbrush again. Hope that helps. Also there are treatments and medication that can help with your cold soars. Ask your dentist.