Drugs have a series of side effects that are sometimes missed in trials. The effects usually surface when the drug is given to a person with a factor that has a chemical reaction with the drug. Usually, such occurrences are rare, which is exactly why they are usually missed in most trials. These side effects are more often than not caught in due time and the drug is revised by the FDA.

Afterwards, the new side effect is included among the pre-existing ones – this is why you will see such side effects such as “massive internal hemorrhaging” on painkillers. These effects are usually much worse as they are the results of combinations of a drug with rare conditions or administration in uncommon circumstances.

Such a side effect was noticed after the administration of well-known, widely-prescribed osteoporosis drug Fosamax. A study was conducted involving patients whose teeth had been pulled. Out of the total number of patients, 4% developed a dangerous and potentially lethal condition called osteonecrosis of the jaw.

These 4% were taking the drug Fosamax, and the condition did not develop in patients whose teeth had been pulled yet hadn’t been administered Fosamax. The osteonecrosis of the jaw is commonly known as jawbone death, and it manifests itself when the jaw fails to heal from minor traumas. The consequences are pain, swelling, infection and exposed bone.

Merck, however, have criticized the study, yet the researchers - Parish P. Sedghizadeh, DDS and colleagues – claim that bisphosphonate drugs hold higher risks than anticipated.