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

It is important to note that if you consult a rational doctor and inform him/her regarding your medical history in detail, it is most likely that he/she may prescribe the correct drug for you, which is less likely to produce an harmful adverse effects. While it is true that no drug is safe and even the mildest drug can produce serious adverse effects if misused or abused, most drugs will not cause serious harm if used correctly.

Just because a drug can produce certain adverse effects one should not hesitate to use it, when it has been prescribed by the doctor. The adverse effects of drugs are listed down in this column as a measure of precaution and not to create panic amongst the users.

IX. Interactions

Whenever a drug is taken along with other drugs or certain foods or alcohol, it is likely that the drug may interact with them and produce effects which are entirely different from those produced when it is taken alone. Many times these interactions may produce beneficial effects which are utilised in the treatment of the patient, for example, for the treatment of high blood pressure, usually more than one drug is prescribed. Other interactions may produce harmful and unwanted effects and hence their occurrence should be avoided. Such interactions may occur not only between two prescription drugs but also between OTC drugs and prescription drugs. It is therefore necessary to read the warnings on the labels of drugs which you are taking and also inform your doctor about all other drugs that you are taking when s/he is prescribing a drug for you. This helps the doctor to choose the right drug for you, which will not interact with other drugs you are taking or at least suggest a dosage regimen where the doses of the two drugs are spaced far enough to avoid an interaction.

Examples of Important (Dangerous) Interactions

Drugs that depress the central nervous system(sleep inducing drugs, narcotics, antihistamines
and alcohol). The effect of two or more of these in combination may be additivecausing dangerous oversation.
Drugs that lower blood sugar levels and suchdrugs as sulfonamides and alcohol. The druginteraction increases the effect of blood sugarlowering drugs, thus further depressing bloodsugar levels.
Oral anticoagulants and other drugs, particularly aspirin
and antibiotics. Because thesedrugs may increase the tendency to bleed, it is essential to check the effects in every case.
(4)   Monoamine Oxidase Inhibitors (MAOIs): Thereis a large
  list of drugs and foods which can produce a severe rise in blood pressure when taken with these drugs. Dangerous drugs include amphetamines and decongestants. Foods that interact include cheese, herring, red wine, beer and chocolate.

This column lists down only the important interactions of the drug with other drugs. (Its interactions with food, alcohol, tobacco, etc., are mentioned under 'Precautions'). The final effect of drug-drug interaction is mentioned along with explanatory/warning notes wherever necessary.

Drug-Nutrient Interactions
Medication Use Effect on Nutritional Status
Alcohol Toxic effect on intestinal lining, altered secretion of digestive enzymes Reduced absorption of vitamin B1, folic acid, vitamin B2, increased excretion of magnesuim and zinc; reduced blood levels of vitamin B12.
Lithium carbonate
Antidepressant Weight gain; altered blood glucose; increased blood levels of magnesium; increased excretion of calcium.
Amphotericin B Antifungal Increased urinary excretion potassium and nitrogen; reduced blood levels of magnesium and potassium.
Antihistamines Nasal Congestion Increases appetite
Barbiturates Anticonvulsant Increased need for folic acid and vitamin D; reduced absorption of vitamin B1; increased excretion of vitamin C.
Metformin, Phenformin
Diabetes Reduces absorption of vitamin B12
Chloramphenicol Antimicrobial Increased need for vitamin B2, vitamin B6, and vitamin B12.
Chlorpromazine Tranquilizer Increased appetite and body weight.
Colchicine Anti-inflammatory Reduces absorption of carotene, sodium, potassium, vitamin B12, lactose.
Colocynth Cathartic Reduces transit time and absorption of nutrients.
Corticosteroids   Reduced absorption of calcium and phosphorus; increased urinary excretion of vitamin C, calcium, potassium, zinc, and nitrogen; reduced blood levels of zinc; increased blood