I had a small cut with a little blood right by my mouth. I ate, with it there and worry maybe blood touched the food and then I ate it.
But then I brushed my teeth and was wiping off my mouth and I smeared the blood by mistake over my lips. I wiped it off a few times but what if some got in my mouth when I licked my lips over night? Does that violate the prohibition of eating blood? I feel terrible that I smeared it by mistake.
It is important to know, that eating human blood is not like eating the blood of an animal. Essentially the prohibition not to eat blood only applies to animals and birds, but not to the blood of fish or humans. The reason we are careful not to eat human blood is because it looks like animal blood- maris ayin. There is an important difference between the two, in places where it is evident that the blood is only human blood, and people seeing it will know that it isn’t animal blood, it is permitted to eat it. For example, the blood that was between your lips, is clearly from you and not an animal, so there is no issue with ingesting it. However, if you bite into a piece of bread and get blood on it, that blood has to be removed, because it can be mixed up with animal blood, etc.
Regarding the blood from the cut near your mouth, since the blood didn’t really leave the body yet, and it is evident that it is blood from you and not an animal, according to most poskim it is not an issue and you don’t have be concerned about it.
שולחן ערוך יורה דעה סימן סו סעיף י דם אדם, אם פירש ממנו אסור משום מראית עין. לפיכך אם נשך הככר בשיניו ויצא דם משיניו על גבי הככר, צריך לגרדו. אבל שבין השינים, מוצצו. בן איש חי (שנה ב’ פר’ טהרות אות א’) – “אם אצבעו מטפטף דם ממנה, יוכל להניח אצבעו בפיו אם הדם מטפטף להדיא, שניכר שהוא מטפטף מאצבעו”.