Have small red blisters inside lips appeared suddenly. What is it?

Hi.

These blisters may be due to many condition. Most probably it is apthous ulcer as majority of people presents with this. This may occur due to multivitamin deficiency or post viral infection.

Are you worried about anything else? Please let me know so that I can clarify it.

Other common conditions may be due to trauma by ill fitting dentures if using or due to any chemicals any drugs or due to herpes. In herpes it will be very painful, in clusters in single side. So if it is both the side then we can rule out herpes.

You can do salt water gargle, drink plenty of fluids, eat more fruits, and take multivitamin tablets. Before taking food apply local anaesthetic agent (i prefer orajel) locally to reduce pain. These will help you. If you have any associated condition then please let me know.

Hope I answered your question. Feel free to ask if you have any query/ question. I will be glad to answer that.
Regards