<s>[INST] I'm taking cephalexin, going to have a tooth pulled in a few days. My dentist suggested breaking open a Benadryl capsule, making a paste to put on my tooth for the pain. It is helping the pain. My concern is this: Will the Benadryl interact badly with the nitrous oxide or laughing gas that he will give me when he pulls my tooth? & will Benadryl interact with the injections he'll give me in my gums to numb them? Also, can I take my antibiotics & Benadryl the day that he pulls my tooth? [/INST] Hello, Welcome Thanks for consulting HCM,    I have gone through your query,  as you are taking benadryl dont worry it contains sedative ingredients , as you are asking for Nitrous oxide it is sedative used as Anaesthetic agent , as you are going for Extraction to denstist you should inform him that medication you are taking before procedure starts ,    As you are asking for interaction of drug no it will not interact with nitrous oxide and you can take antibiotic on that day of extraction also ,    Your duty is to inform your dentist before extraction about medication you have taken,Hope this will help you. Wishing you good health . </s>