I'm 18 years old and weigh 250 lbs. i am allergic to penicillin but have strep throat. what is the correct dose of cephalexin to be taken?

Before it is given,: Some people who are penicillin allergic can have cross allergies to cephalosporins like keflex.

See below: The dose can vary. The frequency of dosing can vary. I would probably treat with 1500 or 2000 milligrams twice a day. But again the dose and frequency varies. Some will give this medication 3 times a day. Hope he gets better.

Take erythromycin: Some penicillin-allergic persons are also allergic to cephalosporins like cephalexin. Its safer to take a macrolide drug like erythromycin, biaxin (clarithromycin) or zithromax.