Allergic to Penicilin. Can I smoke weed?

I don't think weed contains penicillin unless the weed somehow got contaminated with the penicillium fungi on it. So for the majority of the time, you probably won't have an allergic reaction. Just watch out for the presence of green mold on your weed and monitor for allergic symptoms such as hives, itchiness in the throat, swollen lips and tongues, dizziness, etc., and you should be ok.