To cover up a cold sore, you can follow these steps:

1. Use a highly concentrated concealer with a thick, creamy consistency and better coverage.
2. Choose a color to neutralize the redness, such as yellow- or green-based concealer.
3. Finish up with a dusting of finishing powder to help everything set.
4. Use a lip lacquer to provide protection.
5. Cover cold sores with Band-Aids, medicated patches, and cosmetics such as concealer, foundation, and lipstick.
6. Use topical creams and ointments.

You can also wrap some ice in a towel and hold it to your sore for 20 minutes at a time to help the swelling go down. After your cold sore looks a little less noticeable, get an invisible cold sore patch from a drugstore so you can put a protective seal over the blemish.

To cover a cold sore with makeup:
1. Use a small amount of oil, balm, or moisturizer to prime your skin and prevent cracking, splitting, and bleeding.
2. Use a Q-tip to gently remove flaky skin.
3. Allow your skin to dry for at least 1 minute.
4. Lightly dab a small amount of cream concealer onto your sore.

I hope this helps!