Hi. Welcome to HEALTHCARE MAGIC.. I have gone through your query and can understand your concerns.. As per your complain Percocet [Oxycodone and Paracetamol] is a painkiller and it has seen to cause dry mouth as a side effect while Benadry [diphenhydramine] which is an anti-histamine or an anti-allergic and it has side effect over the secretions and seems to reduce the aqueous and mucous secretions of salivary glands leading to dry mouth as well as reduces secretions from tear glands as well as it also reduces aqueous component or precorneal tear film leading to dryness in eyes.. You need not to worry as you have already stopped the intake of the medicine and slowly the symptoms of the side effects will wean off.. As of now you should instill Artificial Tears in your eyes which are available as eye drops and helps in relieving dry eyes.. You can instil them 4 to 5 times a day or less as per the requirement.. For dry mouth and dry throat Saliva Substitutes known as Artificial Saliva containing methyl cellulose should be instilled in mouth for lubrication and relief.. Saliva stimulants like sugar free chewing gums can be chewed throughout the day as it will help in stimulating saliva flow.. Drink plenty of water to maintain hydration.. If the condition does not start improving within a week to 10 days consult a physician and get evaluated.. Hope this information helps.. If you find the answer helpful please give me a Five Star Review and click on found the answer helpful as a token of appreciation.. Thanks and regards.. Dr.Honey Nandwani Arora..