 [ Symptoms ] how long can herpes stay in your system before an outbreak years  been married for 16 12 years no infidelity but he is not my first is it possible to have contracted the virus that long ago and not have an outbreak until today [ Disease ] most helpful answer yes you can take antihistamines like benadryl while taking prednisone i have the same issue i asked the dermatologist and my pcp and they both said it would be safe it helped me sleep much better