Physicians tell their patients to report any unusual
symptoms they may experience when they start taking a new medication,
and go to the ER if the symptoms are severe. Many patients second-guess
themselves and hesitate to follow these instructions because they don't want to
make a fuss or feel silly if the symptoms turn out to be benign. Physicians
generally warn their patients about expected side effects; sometimes the
benefit from the drug outweighs them. An unusual reaction is an unexpected side
effect, and sometimes an allergic reaction.
What is an unusual reaction?
Unusual reactions can be caused by interactions with supplements or another
drug that the patient is taking. It is important to tell physicians about every
drug or supplement; even herbal remedies can interact with some drugs. The
patient might also have kidney or liver problems that mean the drug is
incompletely metabolized or takes longer to clear from the body than expected.
Normal doses of the drug would then cause it to build up in the body over time.
The effects of this type of buildup would depend on the nature of the drug, so
it's important for patients to let their doctors know about any new symptoms
when they start taking a new drug, especially if they are bothersome or distressing.
Systemic reactions such as fever or vomiting should always be reported to the
Allergies to Drugs
Between six and ten percent of unwanted side effects come from drug
allergies. The most frequent drug allergies are to antibiotics such as
penicillin and the cephalosporin. Allergies to
non-steroidal anti-inflammatory drugs such as aspirin and ibuprofen are also
very common. Tell your doctor if you have ever had a reaction to any drug in
these families, as this can be a warning sign of a possibly more serious
reaction to a related drug. Sulfonamides, which include antibiotics, oral
diabetes medications and some diuretics, also sometimes trigger an allergy-like
reaction that currently is not completely understood.
Allergies can take a number of forms, and the symptoms can range in severity
from an annoyance to life-threatening distress. The most frequent symptoms of a
drug allergy are itchiness and a rash. Hives, wheezing and palpitations are
The most serious type of allergic reaction, anaphylaxis or
anaphylactic shock, is usually characterized by difficulty breathing and
sometimes by swelling of the tongue. Difficulty breathing always requires
immediate attention, but anaphylaxis can quickly progress into shock and
cardiac arrest. These dangerous reactions generally happen within four hours,
most often in the first hour, sometimes within minutes. Anyone who suspects an
anaphylactic reaction should call an ambulance. Penicillin is the most frequent culprit in this type of reaction.
Generally though, allergies don't prove to be fatal. However, severe allergies
can cause a great deal of misery. The immune system of allergy sufferers
mistakenly believes that the body is under attack, and the mast cells produce
substances to help the body fight off its attackers. Usually the substance is
histamine, which can cause itching, inflammation, sneezing and respiratory
Other possible signs of an allergy include abdominal pain, vomiting, watery
eyes and hoarseness. Dizziness, rapid pulse and shortness of breath are
possibly signs of a serious reaction. Someone should drive the patient to the
Since an allergic reaction requires a prior exposure to a substance, a reaction
that occurs the first time a drug is taken probably is not the result of an
allergy. However, sometimes patients do not remember the first time they were
exposed, since the exposure on that occasion did not cause them any symptoms.