For Quality, Essential, Generic Medicines
Chapter 1: About Drugs in General    
Annexure 1

Some Common Drug Categories And How They Work

This appendix is a brief description of some of the more common drug categories one is likely to come across:

Analgesics: Painkillers Antibiotics
Laxatives Antianemics
Antiemetics Steroids
Antacids and antiulcer drugs  

Analgesics (Painkillers)

Pain is an unpleasant symptom and not a disease. Pain suggests some disturbance in the body. It is hence necessary to correct this disturbance to cure the pain. A painkiller drug gives you only temporary relief from pain, e.g., the pain of toothache can be relieved by pain-killer but can only be cured by appropriate dental treatment.

It is therefore, important to determine the cause of pain in all cases. However this is not always very easy. Hence painkillers play a very important role in providing immediate relief to the patient till the cause is found and treated. Sometimes, when the underlying cause is irreversible, long-term analgesic treatment may be necessary.

Types of Analgesics

The main two types of analgesics are Narcotics and Non-Narcotics.

Narcotics are very strong analgesics. They are available only on doctor's prescription, since they are habit-forming and exert other harmful adverse effects too.

Non-Narcotic analgesics are less powerful and they include aspirin, paracetamol and non-steroidal anti-inflammatory drugs (NSAIDs). They are OTC drugs and hence widely used. Whenever one uses OTC analgesics to treat pain, one must always consult the doctor if the pain persists for more than 48 hours after taking the drug.

While treating pain, treatment is first started with a non-narcotic. If that is not sufficient to relieve pain a strong narcotic may be used. Thus narcotic analgesics are used only to treat very severe or long lasting continuous pain like post-operative pain (pain after surgery) or pain in cancer, etc.

A doctor weighs the risk-benefit ratio of using a narcotic analgesic and decides to use it in a patient who, he feels, is miserable with a pain that would be more harmful than the side effects of the narcotic drug. Sometimes elderly persons whose health is deteriorating day by day and who have very little chances of survival are given injections of narcotic analgesics so that they die peacefully (however, this is not legal in India as yet).


It is the most common type of pain that occurs in a majority of individuals. Over-the-counter analgesics are widely consumed for headaches. Hence we shall discuss 'headaches' briefly.

Headaches can be broken into 3 major categories:

1. Tension or Muscle Contraction Headaches: They are caused by busy, demanding schedules, worries and emotional upsets. The pain is usually constant, with a pressure like feeling primarily in the front but sometimes at the top and in the neck, and varying only in intensity throughout the attack. Dizziness and light-headedness may also occur.

2. Vascular Headaches: They are blood-related headaches and include migraine, cluster and toxic types of headache.

3. Headaches due to physical and organic conditions

Migraine headaches last from several hours to several days with severe, throbbing pain on one side of the head accompanied by nausea, vomiting, sensitivity to light and limited ability to function normally. Spots and flashes, speech difficulties and loss of feeling may be warning signs of an attack.

Cluster headaches occur in clusters, that is, one to three headaches a day, each lasting from ten minutes to few hours. The pain is similar to migraine related pain and the symptoms include flushing of the forehead, tearing of the eyes and nasal congestion.

Toxic headaches occur due to various reasons, some of which are listed below:

Chemical from food

  - Fumes from industrial plants or engine exhaust  
  - Substances in food such as cheese and bananas as well as fermented products such as red  
  - Nitrite preservatives commonly used in processed meat and the flavour enhancer monosodium  
    glutamate (MSG) in prepared food.  
  - Alcohol, cigarettes  
  - Allergies to various pollens, moulds, or other substances are also triggering factors when  
    headaches are seasonal.  
  - Changes in attitude and weather  
  - Hunger (for long periods)  

Headaches due to physical (organic) diseases or conditions may result from

Fever associated with an infection

  - Problems of the ears  


  - Teeth  
  - Facial nerves  
  - Injuries  
  - Eye problems  
  - Anaemia  
  - More serious health problems (rarely)  
  When should you consult the doctor?  
  A doctor should be consulted when:  
  - Headache continues for 48 hours after taking the recommended dose of painkillers, or returns  
  - Headaches occur frequently  
  - Headaches interrupt sleep or impair one's ability to function normally  
  - Headaches are accompanied by fever, vomiting, weakness, dizziness, numbness, loss in balance  
    or any unusual sensations.