A pain reliever is a drug that reduces pain without causing unconsciousness or complete loss of feeling. In medical terminology, they are called analgesics. There are two main types of analgesics: The peripherally-acting analgesics or non-narcotic pain-relievers and the centrally acting analgesics or narcotic pain-relievers.
The first type acts on any pain associated with muscles or bones or their related structures. Hence these are called peripherally-acting analgesics or ‘mild analgesics’. The most common of these is aspirin. Its active constituent is acetylsalicylic acid. It was first synthesized in 1899, and produced in huge commercial quantities ever since. Other analgesics of this group include analgin and paracetamol. These are used to relieve headaches, rheumatism and other body pains.
The second groups of pain killers, the centrally-acting analgesics are very potent drugs and include substances derived from opium, an extract of the poppy plant. Two such analgesics are morphine and heroin. In the brain they depress the activity of the cortex, and thalamus which is the part that receives messages from the body’s pain receptors. They are very effective and act instantly when injected into a muscle or vein. They are only used by physicians for relieving intense pain of those suffering from cancer, heart attack or severe injuries involving broken bones or wounds. Some common drugs of this group are Codeine, Pentazocine and Ethoheptazine.
Both types of analgesics have a number of side effects. For example, aspirin can irritate the stomach, cause indigestion or in serious cases it may even lead to an ulcer. If used indiscriminately, it may cause anaemia.
Morphine drugs can cause nausea and vomiting, but this side-effect can be blocked by giving the drug Cyclizine along with it. Morphine and its allied drugs can cause addiction when used over a prolonged period.
Some other analgesics such as antipyretics are used to bring down fever. In severe cases or while carrying out a surgical operation, doctors apply many anaesthetic drugs to deaden pain.
These drugs are available under different brand names. Aspirin is available in the brand name of Disprin, Mejoral etc.; paracetamol is available in the name of Calpol, Crocin etc. Novalgin is an analgin whereas Fortwin is a brand of Pentazocine. It is always advisable to check the constituents before buying these drugs.