The formal term for painkillers is analgesics, a word derived from the Greek words an (without) and algia (pain). The three most commonly used types of pain medicine today are the nonsteroidal anti-inflammatory drugs (NSAIDs), the paracetamol based drugs and the opioid drugs.

The nonsteroidal anti-inflammatory drug (NSAIDs) group contains a wide range of different painkillers. Examples of commonly known NSAID painkillers are Aspirin, Diclofenac and Ibuprofen. NSAID pain killers do not only alleviate pain; they will also lower fever and decrease inflammations. They are called non-steroidal in order to discern them from the steroids, since the steroids are also used for their anti-inflammatory capacity. Aspirin was discovered in 1829 when salicylic acid was chemically isolated for the first time, but willow bark containing salicylic acid has been used as a pain killer long before the 19th century. A lot of NSAIDs are available over-the-counter but this does not mean that they are harmless. When misused, even comparatively weak NSAIDs can have severe side effects, including bleeding ulcers and photosensitivity. NSAIDs are generally not recommended during pregnancy.

Paracetamol is also known as acetaminophen. Both words are derived from the chemical name for this painkilling compound: N-acetyl-para-aminophenol and para-acetyl-amino-phenol. Two examples of commonly known brand names under which Paracetamol is marketed are Tylenol and Panadol. Painkillers containing Paracetamol will relieve pain and decrease a fever, but unlike the NSAID painkillers they have no anti-inflammatory properties. One of the advantages of Paracetamol compared to NSAIDs is that Paracetamol painkillers will not affect the bloods ability to clot. Nor will they damage the kidney or lining of the stomach as long as you stay within the recommended limits and never use too much Paracetamol. High doses of Paracetamol will however be damaging to a wide range of bodily functions. Paracetamol should never be combined with alcohol since the liver will be overloaded with the burden of breaking down both alcohol and Paracetamol, which makes the risk of Paracetamol poisoning higher. If you are healthy, well-nourished and do not drink alcohol, a single 10 gram dose of Paracetamol can cause significant liver damage.

Opioid drugs are very potent painkillers but will come with a sever side effects, even in low concentrations. Morphine is one of the most commonly used opioids in pain killing drugs. An example of a morphine based painkiller is Tramal. Pethidine is another pain killing opiate and can be found in medications such as Alodan and Demerol. Morphine will act directly on the central nervous system and can relieve even sever pains, such as post surgery pains and cancer pains. Morphine is addictive and it is important that it is used with caution. The addiction can be physical as well as physiological. The side effects are also both physical and psychological. Among the physical side effects are constipation and an inhibition of the cough reflex. Psychological side effects include euphoria as well as nightmares, and drowsiness can come hand in hand with insomnia. Morphine was isolated from opium in 1803 by Friedrich Serturner, a German pharmacist. He named it morphium after the Greek god of dreams, Morpheus. Serturner soon discovered its usefulness as a painkiller, but morphine didnt grow really popular until the hypodermic needle was invented in 1853.