How can I get my dog to take his meds if he absolutely refuses to take them orally?

My dog has been bitten by something and his face, throat and chest have swollen. I have taken him to the vet where he was knocked out and the vet checked for a remaining sting. He could not find one and concluded that he may have been bitten by an adder. He has given him some meds but he refuses to take them. He is very, very weak and its been 4 days since he has eaten anything. He is drinking water. I was wondering if there is any place apart from his gums, where I can rub the meds in so that his body will absorb them. He is also old (14 years) and I don't want to distress him by forcing meds into him. HELP PLEASE HE'S MY FRIEND.