The following is a fictional story about someone who had been told since birth he/she was allergic to penicillin and as a result during those few doctor visits would always mention 'penicillin!' when asked about allergies. [Told in first person for dramatic effect]
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So, I get sick about a month ago. No big deal - it happens once every few years. Phlegm, yellow stuff hacked up. My treatment is to up onion, garlic, tumeric and any kind of pepper (fried serrano chilies get the mucous gunk loosened up in your airways). If it gets worse then it's always good to have some OTC 'severe cold & flu' pills/gellcaps around. It finally goes away after a few weeks. Again no biggie.
About the time it went away I noticed a pain coming from right set of ribs closer to the sternum. Tested for lung cancer/something-wrong-with-lungs by expanding the diaphragm where your upper chest rib muscles don't do much work (only your stomach will expand with this type of breathing - not your upper chest). Lungs expanded - no pain. Tested by breathing expanding upper chest and felt pain. Sneezing also caused pain. Area of pain about fist sized (in area).
So, I let it ride for a week. It seemed to expand a bit in pain area. Thought about ER/Urgent Care visit. All I needed was an X-ray then the internet but I don't think you get something like that without 'orders' or an 'auth'. Anyways, asked a family I know if they had any antibiotics - they've got a bunch of kids and there's always some meds around. All they had was some left-over penicillin from mom only a couple of months old.
Now, awhile ago when I recited 'penicillin' to the question, the nurse mentioned that immune systems can change and something you tested allergic for years might be OK now and vice versa ('We'll still go with the cephalexin').
I finally got to test that theory. Took a small (maybe 1/3) bite of 250 mg PCN Sunday afternoon. Waited a few hours - no nothing as far as abnormal symptoms/signs. About 12 hrs. later took the remaining 2/3. Nothing again. So right now following the 'scrip of one 250 mg per 6 hrs until gone.
It's Tuesday evening and the pain area has been receding slowly but noticeably over the past 72 hrs.. Placebo? Maybe - but I let it ride for about a week and half before trying the PCN.
Assuming it does take care of it we can hypothesize some probable conclusions: Infection was bacterial not viral. Infection/pain was/is in the interstitial muscles [that's what makes the good eats in 'ribs']. I did have pleurisy once as a kid but that's more of an infection of the sac that holds your lungs so it would have hurt when the lungs were expanded without using upper chest muscles.
Long story short: I'm definitely not allergic to PCN (anymore) and it may be killing whatever nasties are in my middle right rib/chest area that may have been a result of nasty cold/flu.
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