At the request of others, I am posting this in a main discussion. Many people do not seem to be aware of the toxic effects over-the-counter pain medications for humans can have on our four-legged friends. Many pain medications that we take regularly can be fatal to dogs and cats. I have personally seen at least 2 dogs die from receiving Tylenol or Ibuprofen. One family lost their 4 year old lab because they gave it Ibuprofen for a few days for pain instead of consulting with their vet. After 3 days of intensive care, the kidney damage was too severe to save him. Here are bits and pieces of an article about a couple of human medications:

The Hazards of Ibuprofen

People pop over-the-counter and prescription pain killers so routinely that they often assume that these pain relievers are safe for a dog suffering from arthritis. They're not. Pet owners who give non-prescription pain relievers like ibuprofen to their dog or cat can jeopardize their health and lives.

Over-the-counter pain relievers like Ibuprofen can have serious side effects for a dog. Over-the-counter pain relievers like Ibuprofen can poison a dog or cause serious or deadly complications such as heart failure, liver failure, kidney disease, dehydration, diarrhea or urinary obstruction.

Jill A. Richardson, Veterinary Poison Information Specialist for the ASPCA National Animal Poison Control Center states that "Less than one regular strength ibuprofen (200mg) could cause stomach ulcers in a 10lb dog, and about six could cause kidney failure."

Never give a dog ibuprofen (Motrin, Advil, Nuprin), naproxen (Aleve), or acetaminophen (Tylenol). Even a child's dose can be fatal. These pain relievers can cause severe, even fatal, stomach ulcers and kidney damage in dogs.

According to the American Veterinary Medical Association, drug poisoning is the most common small animal poison exposure.

A dogs body does not utilize or tolerate Ibuprofen the same way a human body does, so the drug that relieves pain in humans can poison a dog or build to toxic levels in a dog.

In one review of ASPCA Animal Poison Control data, ibuprofen was the most common drug involved in drug exposure to dogs and cats. Dogs were the animals most commonly poisoned by Ibuprofen, and most exposures were acute.

The NSAID (nonsteroidal anti-inflammatory drug) Ibuprofen is commonly used in humans for short-term management of pain and fever and for long-term control of arthritic pain.

In humans, ibuprofen taken at standard dosages appears to have a wide margin of safety. In a dog, ibuprofen has a very narrow margin of safety. Ibuprofen metabolizes slowly, which increases the risk that toxic levels will be reached.

Symptoms of Ibuprofen Toxicity in a Dog

Staggering, Increased thirst, Increased frequency of urination, Digestive upset, Bloody stool, Listlessness, Liver disease, Kidney disease, Seizures

Induce vomiting if possible and seek immediate veterinary help.

When to Induce Vomiting

In many cases inducing vomiting has been recommended. This should never be done if the dog is listless, unconscious, or in a stupor. Also, if you suspect cleaning products, hydrocarbon fluids (motor oil kerosene, gasoline), strong acids or alkali, you should not induce vomiting. Always consult with a veterinarian before proceeding, and we suggest you follow his instructions to induce or not to induce vomiting.

What to Use

One common method is to mix 1 teaspoon of hydrogen peroxide with 1 teaspoon of milk if available - you may need to force feed with an eyedropper.

Signs of toxicity have been seen with as low a dosage as 8 mg/kg/day for 30 days. In one case report, a dog given 3mg/kg every other day for six weeks developed a fatal gastric perforation. Cats are thought to be twice as sensitive as dogs to ibuprofen’s toxic effects.

In some cases, Ibuprofen was administered to pets in the mistaken belief that it was safer than aspirin. In other cases, the dogs ate the Ibuprofen on their own accord. Some ibuprofen tablets are coated with sugar and appeal to dogs. It is important that dog owners keep Ibuprofen out of a dog’s reach.

Low dosages of NSAIDs are sometimes prescribed by veterinarians to relieve pain. Please use extreme caution. These drugs can cause ulcers, damage to the kidneys and other organs, suppress bone marrow; and cause bleeding disorders.

There is no need to subject your beloved dog to such dangers with safe and effective natural options available like glucosamine and chondroitin or turmeric. If your veterinarian prescribes a medication, ask him or her about the use of Arthritin, or another safe glucosamine and chondroitin supplement.

The Hazards of Acetaminophen (Tylenol)

When we aren't feeling so well, we reach for something like aspirin or Tylenol, or Ibuprofen (NSAIDS or non steroidal anti-inflammatory drugs)so why not give kitty a bit to help her out? Many well meaning pet owners do just that, and end up poisoning their pets.

Tylenol (acetaminophen) and Ibuprofen toxicity is due to an active metabolite made by the liver from the drug. This metabolite causes severe damage to liver cells and red blood cells. Dogs tend to have more liver damage, whereas cat's red blood cells undergo a transformation of their normal oxygen carrying hemoglobin to a non functional form called methemoglobin. One Children's Tylenol tablet contains almost twice the toxic level for a normal sized cat per kilogram of body weight, and the adult size Tylenol has more than six times the toxic level!

The following quotes are all from the American Veterinary Medical Association: http://www.avma.org "Animal poisoning by drugs is by far the most common type of small animal poison exposure, accounting for 75% of 1990 toxin exposures as reported by the AAPCC and 82 of 425 fatalities.""Due to the significant toxicity to pets in relatively minimal dosages, the recommendation is clear — Tylenol should not be given to dogs or cats. "

Acetaminophen can be toxic to dogs

Read the label of any other medicine you are using to see if it contains acetaminophen, sometimes abbreviated as APAP, diphenhydramine, or phenylephrine. 　

Possible symptoms: Vomiting, Diarrhea, Difficulty in breathing, Dark colored urine, Listlessness

If your pet ingests Tylenol, get them to a veterinarian right away for emergency treatment. The problem is more acute and life threatening in cats than in dogs (though by no means safe in your canine companion).

NEVER Give Cats Aspirin!

Toxicity signs which can occur within 1-2 hours after ingestion

Salivation, Vomiting, Bluish coloured gums, Severe depression, Dark colored urine, Swollen face and paws

Aspirin has a long half life in cats, at least 24 to 48 hours, so it will reach toxic levels pretty quickly if it is given more frequently than once every 48 hours and the dosage is 10mg/lb so a baby aspirin (81mg) is a much more appropriate dosage for a cat than an adult aspirin.

“The elimination half-life of aspirin in cats approaches 40 hours, compared with 7.5 hours in dogs. In veterinary medicine, aspirin is used primarily for the relief of mild to moderate pain associated with musculoskeletal inflammation or osteoarthritis. Because aspirin is not approved for veterinary use, definitive efficacy studies have not been performed to establish effective dosages.”

http://merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/191606.htm Merck Veterinary Manual

I have not seen much information on Ibuprofen and cats but it is a good idea to avoid all non-steroidal anti-inflammatory medications in cats, at least until one of them does prove to be safe in someone's clinical trials. Buffered aspirin (salicylic acid) is often given to dogs but the dosage MUST be carefully calculated by your vet. Ibuprofen, is sometimes prescribed for dogs, in closely monitored doses, and should never be given to cats."

If your pet ingests aspirin in an over dosage, call your vet for treatment. Untreated overdoses can result in stomach ulcers, severe kidney damage, and liver disease. The same holds true for Ibuprofen, which is never prescribed for pets. Be careful of accidental ingestion too, tablets like Advil are coated in a sweet tasting shell, and dogs may just eat them like candy if they are left around for an inquisitive pooch! 

Many believe that what helps us will also help our pet. In some instances, the drugs we take and what our pet receives is identical but in considerably smaller doses.

http://www.spine-health.com/treatment/pain-medication/types-nsaids

COX-1 and COX-2 Inhibitors (drugs mentioned below are NSAID's for pets)

Zubrin (tepoxalin), Previcox (firocoxib), Metacam (meloxicam), Deramaxx (deracoxib), Rimadyl (carprofen), Celecoxib (celebrex), Valdecoxib (bextra-withdrawn from market in 2005), Rofecoxib (vioxx-withdrawn from market in 2004)