Am I allergic to penicillin too?

I just found out that I have an allergy to Cephalexin (antibiotic). People with allergies to penicillin are also allergic to Cephalexin, but I want to know if the reverse is also true. My sis and dau both are allergic to penicillin, but I myself have never had a reaction to penicillin. I've also had Cephalexin before and never had a reaction to that too. Just got out of the ER today. Had to get an EPI shot, Benadryl through the IV, and a steroid. I'm sporting a major poison ivy rash and some of the blisters popped and got infected. I was having problems breathing, throat closing up, my tongue swelled, had a taste like paint in my mouth and my rash turned into this major ugly, swollen, angry, beet-red/purplish color. All but the rash itself cleared up in an hour or two at the ER. Now on a steroid for the poison ivy rash and off the antibiotics. I've Googled but cannot find an answer to my question: If someone is allergic to Cephalexin, are they now alleric to penicillin too? Thanks!

Allergic reactions to penicillin antibiotics are common. Cephalosporins are other antibiotics that fight many of the same infections as penicillin. They may be an option for patients who are allergic to penicillin. However, cephalosporins and penicillins have similar chemical structures. Some patients who are allergic to penicillin are also allergic to cephalosporin, but information about the frequency of cephalosporin allergy in patients with penicillin allergy is limited. With some drugs, such as penicillin and cephalosporin, doctors can perform a "skin test" for allergic reactions by administering small amounts of the drug under the skin. However, rather than perform a skin test, many doctors simply avoid cephalosporin in patients with penicillin allergy.

Wow, you really had a rough time of it.

Cephalosporins are chemically related to Penicillin, but are not exactly the same. I am allergic to penicillin, but can take Cephalaxin cautiously. Your reaction to the Cephalexin was pretty severe. I'd ask your doctor for testing for a penicillin allergy before I would risk taking it again.

wow

You aren't necessarily allergic to both. I can take cephalosporins but not "-cillins" Because of the severity of your reaction I would also be very careful if you do need penicillin. (I would recommend never getting an injection of penicillin and making sure you are close to an emergency room if you would need to take the tablets). Unfortunately there is no test for drug allergies. You should certainly ask your physician for her/his opinion to whether or not you should avoid penicillin. Hope you're feeling better soon!

it is VERY probable - they have a similar chemical structure - i would suggest that you have a 'skin test' to determine which antibiotics you are allergic too