General activity of a drug is affected when its is administered with another drug or food, herbal medicine etc, this is termed as Drug Interaction.
Many drug interactions are harmless and the percentage of harmful interactions is very less also the severity of an interaction varies from one patient to another.
Interaction between the drugs can cause an increase in the effect of one or both drug.
On interaction when a drug blocks the effect of another drug is known as antagonism.
Nature of interactions may be Pharmacodynamic or Pharmacokinetic.
Interactions are happening between drugs of same class or drugs with similar pharmacological effects. Drugs of same nature show Competition at the receptor sites or at the physiological site and this is the main reason for Pharmacodynamic interaction.
Interactions of one drug alters the absorption, distribution, metabolism, or excretion of another drug, thus it alters (increases or decreases) the availability of to produce its pharmacological effects.
Whether you're looking for a doctor for dealing with your own medical condition, click here to find right physician.
It is any effect of a drug, chemical, or other medicine that is in addition to its intended effect, especially an effect that is harmful or unpleasant.