How does a side effect occurs?

What is a drug

         Drug is derived from a french word drogue which means a dry herb.It is an active chemical substance used for treating different kinds of diseases. A drug can be taken by different routes like oral(through mouth), injections (muscular,intravenous), topical, rectal (suppository) etc., The drug administered will show the action by two main mechanisms.
1. Pharmacodynamis – Mechanism of how a drug acts and treats the disease.
2. Pharmacokinetics – A-Absorption,D- Distribution,M – Metabolism ,E – Excretion of drug.  

What is a Side effect

             An undesirable ,harmful effect produced by a drug along with normal therapeutic action at normal human doses.Has to be treated either by reducing or stop the drug intake and may require treatment at severe condition.

How a drug toxicity occurs

         A drug taken by any route has to be Absorbed into the blood either through intestine or skin, reaches the blood circulation , Has to be Distributed in blood by binding to plama proteins (albumin,globulin),Metabolised(degraded)to separate the active chemical moeity from additives,shows the action and finally gets Excreted through the kidneys in the form of urine waste.If the drug remains in the plasma for more time  it leads  to toxicity. This drug accumulation in blood plasma  due to repeated  and higher doses, ,will produce several side effects.

How a drug gets Approved

       A drug must be approved by FDA (Food and Drug Administration) before getting marketed.The NDA (New Drug Application) must be filed by pharmaceutical companies only after submitting the clinical evidence that the drug have therapeutic activity and it is safe. If any side effect of drug is not reported by the pharmaceutical company to FDA may lead to prosecution.Many drugs have been withdrawn from the the market due to the serious side effects they have produced. For example, 
Rezulin an anti-diabetic drug have been withdrawn from the market after 3 years due to the liver toxicity. 
Omniflox,an antibiotic against pneumonia and other respiratory infections,have been withdrawn fom the market after 3 months due to their toxic effects on kidney and blood cells (anaemia).

Drugs and their Toxicities

     Most of the drugs preferred through oral route of administration has Nausea (vomiting sensation) and vomiting are general and common side effects. Apart from these headache,dizziness, allergic reactions,liver and kidney toxicities etc.,here we will observe some of the common drugs and their side effects.
  • Aspirin –  Heartburn,ulcers, Allergy,internal bleeding,liver,kidney toxicity.
  • Paracetamol – Allergy,Gastrointestinal bleeding, kidney toxicity. 
  • Cetrizine –Drowsiness,tiredness,dry-mouth,sorethroat,cough,headache ,constipation.
  • LevothyroxineHeadache,Insomnia,Nervousness,Increased sweating,Bone pains.
  • Metformin(diabetes) –   Kidney complications,tiredness,metallic taste.
  • Esomeprazole(ulcer) –  Confusion,fast heart rate,Diarrhoea,muscle cramps.

Surprising good Side effects

           All the side effects are not dreadful and harmful.  Some drugs may have useful side effects also. Confused ? 
Minoxidil , marketed for treating high blood pressure but produced a side effect of hair growth. Now it have been used as topical lotion for treating baldness.

Aspirin a normal anti-inflammatory drug, have been decreased the mortality rate of prostate cancers. Daily dose of Aspirin activates a protein which inhibits cancer cell growth.
Paroxetine , used to treat depression have been found effective in lowering the risk of heart failures as it have the ability to inhibit an enzyme GRK2 which was found to be overproduced during heart failures.

How to deal with Adverse effects

  • Many drugs causes disturbances in the stomach causing nausea, vomiting,ulcers, diarrhoea etc., Always prefer to take the medication along with the food as it may reduces gatric secretion due to drugs,unless prescribed to take on empty stomach. 
  • Avoid alchohol consumption, Caffeine,stimulants,citrus fruits and spicy food.
  • Ask tour doctor about the side effects of prescribed drugs and consult immediately of any severe condition of those effects.
  • Ask for an alternative safe medicine to get rid of side effects of persistent drug.
  • Adsorbants like Activated charcoal will be preferred in case acute poisoning of higher doses of drug.
  • Colorful coated medicines and syrups may attract your child.keep out of children.
  • Drink plenty of water and fluids to eliminate toxic substances from your body.                                                                                                                                                                                                                 


         Anything used in limit will certainly helps mankind.Excessive intake(either repeated dose or high dose) may leads to toxicity of drugs producing side effects. Do not go for self medication and ask your doctor for a safer alternative drug if you have trouble with some drug.Stay healthy and safe.

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