I'm so glad you asked first
Tylenol/acetaminophen and Ibuprofen (Motrin, Advil, Nuprin, etc) should never be given to a dog.
Benadryl ( Diphenhydramine, for allergies) should never be given without a veterinary recommendation. Doseage is typically .50 to 2 mg per pound of body weight just one or two times a day. A baby measuring spoon/eye dropper, medication delivery device is recommended to assure proper administration.
- Remember, side effects may be life threatening. It should never be given without a veterinarian recommending it -
Some medical professionals may administer NSAIDS for pain relief, but they know what they're doing and have access to different doses. Few people realize that two regular aspirin may kill a small dog.
Dogs tolerate simple (acetylsalicylic acid) aspirin products (offered only on occasion; they may cause stomach upset or ulcers if given too frequently, plus they are a blood thinner, so it may completely inappropriate in some animals).
An 8 lb dog would generally be given ½ of a baby aspirin (40 mg) or less. Your companion should be ok with a single baby aspirin at her weight, but just one and then follow up with your vet.
Before treating him yourself though, you should really make sure there's a reason to.
If you don't have a thermometer specifically for animal use, you're going to convert the current ‘people' plastic digital thermometer right now. You can always pick up another people thermometer tomorrow, but at this moment, you're going to take your companion's temp.
Put a dab of KY Jelly or even petroleum jelly at the tip. In a pinch, a bit of cooking oil will do. Make sure the thermometer is ‘on' and insert it about 1" into the anus, ever so gently and while soothing them, keeping things calm.
Normal temps for both dogs and cats are between 100.5 and 102.5
Above 102.5 but below 103.5 can probably be watched at home; however, anything over that really should be evaluated by a vet. At least put a call into your vet for further advice which he/she will be better able to give you since they have a record of your individual companion and know the latest physical/health history.