My lips swelled up out-of-the-blue a week ago. I'm thinking it was a sun allergy because I'd just come from a 4-day seaside vacation. And, although I was very good with sunscreen on most of my body, I feel I may have neglected my lips. I'm pretty sure it's not a food allergy as I ate very simply that day (I did have a couple walnuts but I'd been eating walnuts all weekend, and most of my life, and nothing occurred.) I've been trying to treat naturally with aloe and stinging nettle drops (natural antihistamine). The swelling has mostly disappeared, however, a blister still remains on my upper lip as well as some sensitivity and numbness. (FYI three clear blisters formed while my lips were swollen but all have healed except for one). Wondering what this might be and if taking Benadryl at this point might still be helpful?