Question about possible delayed reaction to Penicillin V
About 2 years ago, I took Penicillin V for an infection. The day after taking my first dose, I noticed that the left side of my lower lip became swollen. It was only the left side of the lip, and I didn’t have any other symptoms — no rash, hives, breathing problems, throat swelling, dizziness, etc.
I usually break the tablet in my mouth before swallowing it. My family doctor thought that perhaps the tablet had irritated the inside of my mouth/lip because I broke it, while another doctor told me that this was not really possible and that it was more likely an allergic reaction.
I continued taking the Penicillin V for another 5–7 days (I don’t remember the exact duration), and I did not develop any other symptoms. The swelling went away on its own within about 1–2 days.
Afterwards, I had a blood test for penicillin-specific IgE, which was negative. However, I was told that a negative IgE test does not necessarily rule out a penicillin allergy, especially if the reaction was delayed.
What do you think — does this sound like a possible allergic reaction to Penicillin V, or could it realistically have been local irritation from breaking the tablet in my mouth?
Should I avoid Penicillin V and other penicillin antibiotics in the future, or would it be worth seeing an allergist for proper testing/challenge?
I’m also quite anxious about taking other medications now. For example, I need to take medication for parasites and I’m worried because I have heard that some antiparasitic drugs may be chemically related to antibiotics. Is there actually any significant connection between antiparasitic medications and penicillin allergy?
I’d really appreciate opinions from people who have had a similar delayed reaction or from doctors/allergists.