Is benadryl (diphenhydramine) at 200mg good to take with asthma? thanks.

Depends on situation: Antihistamines have a drying effect & can cause a thickening of the respiratory mucous that is already a problem for some asthmatics. When asthma is well controlled & the occasional allergic issue arises, i see no problem using benedryl. I don't recommend it to those that are symptomatic with their asthma.

Dosage?: Are you sure about the dose of 200mg? Regardless, the use of antihistamines in asthma does have a place. Often an asthmatic's "trigger" is an allergy (animal dander, dust mites, etc). Benadryl (diphenhydramine) is an excellent product but be mindful that it can make you sleepy. You may want to try a product like Claritin which mas a minimum of that kind of side effect.