Modern science has gifted man with marvelous therapeutic drugs to alleviate his pain
Diseases which would have killed the victim a few decades back are now cured in a matter of weeks by these wonder drugs. But there are two sides to the coin. A lot of these drugs though highly efficacious have unpleasant side effects one of them being allergies. For example one of the most common offending drug is penicillin.
First a few words about allergies. What you have to remember is that allergy is caused by your body’s own immune system running amok The human body’s own immune system consists of two types of cells B lymphocytes and T lymphocytes. The B lymphocytes produce antibodies which are protein molecules called immunoglobulins. They bind to the cell membrane of the offending invader cell eg bacterial cell, rupturing the cell membrane thus killing the cell. The T lymphocytes produce cells which phagocytose or engulf the invading cell thus destroying it. Now the question arises that from where do these lymphocytes get the information about which cell to attack and which not to. The answer lies in the fact that copies of the cells primed for one class of pathogens are stored as memory or template after an initial attack ready for the next assault.
Likewise memory cells are formed for the drug molecules are formed after the first round of treatment with these drugs. When there is another round of treatment the memory cells mount an exaggerated response to the drug molecule, so much so that the bodies own tissues are attacked. This is the basis for allergic responses.
The symptoms of drug allergies may be mild or life threatening. They usually occur from 1 to 72 hours.
The most common symptoms of drug allergy are skin rashes, followed by hives or utricaria, blisters and eczema. . Next in the order of seriousness are fever, cough, running nose, difficulty in breathing and wheezing. More serious are life threatening reactions like anaphylaxis and toxic epidermal necrolysis. Drug allergies can also affect the liver, kidneys and the lymphatic system.
More systematic manifestations of drug allergies include autoimmune disorders such as SLE, vasculitis and myasthenia gravis. Red blood cells and platelets may also be destroyed by drug allergies leading to hemolytic anemia and thrombocytopenia.
The treatments for all the minor disorders are anti allergic tablets or administration of steroids.
Let us consider the ailments one by one.
The best thing to do in case of a drug allergy is to stop taking the drugs. It is not always that simple.
Rashes or eczema of the skin respond to anti allergic tablets like pheniramine malleate or mast cell stabilizers.
Hives or utricaria occur when the allergic antibodies rupture mast cells containing the chemical serotonin. These chemicals relax the smooth muscle cells in capillary walls leading to leakage of fluid and causing lumps or hives. The treatment for this is an intravenous injection of steroids. Steroids act my reducing what is called the inflammatory response of the tissues decreasing the allergic response.
Body aches and fever respond to paracetamol tablets.
Autoimmune disorders like drug induced SLE is a serious problem. The mechanism for this has already been explained which is the fact that the immune system attacks the bodies own tissues. It is a multisystem disease attacking the kidneys,heart,lungs joints and the nervous system.
There is no permanent cure for SLE and the only treatment that is offered is a palliative one.
Anaphylaxis is the most dangerous drug allergy. Actually it is a severe form of hives, but here the respiratory system is compromised Constriction of the bronchus or air pipe takes place leading to impairment of breathing. This is a medical emergency which can result in death The treatment for this is an injection of adrenaline.
Myasthenia gravis is another problem that can be caused by drug allergy. Here the problem is paralysis of respiratory muscles caused by autoimmune attack. The prescribed treatment is plasmapheresis to weed out the offending auto-antibody.
Toxic epidermal necrolysis is also a dangerous drug reaction where layers of the skin peel off in an allergic reaction to corticosteroids.
So symptoms of drug allergies are many and varied but fear not –most of them can be treated.