what are drug allergies

Drug Allergies


Risk vs. benefit.

So goes the credo when deciding whether to use a medication. All things taken into account, including the disease—untreated vs. treated, the side effects, the allergic reactions, and the untoward effects, it will either be better or worse for a person to take any medication.


Aren’t you what you eat?

We have evolved as a self-contained bag of processes, using biochemistry to make energy, regulate processes, and control organs. Introducing a substance that has a chemistry that isn’t the same is going to get noticed by your body. Thankfully, whether helpful or not, your body uses three main things to eliminate danger:

Gastrointestinal—digestive acids and the filtering absorption properties of stomach and intestinal cells can modify medication taken orally.


You are not what you absorb!


Hepatic—the liver alters the molecules of foreign chemicals so that they can be excreted into the colon for elimination via the feces or delivered to the kidneys to be filtered out and urinated away.


You are what you don’t detoxify!


Renal—the kidneys will clear many foreign molecules, filtering them out of the blood and dumping them into the urine.


You are what you keep!


These three filters, the GI on the front end, the hepatic in the middle, and the renal on the hind end, alters any alien biochemistry, sometimes to better working molecules, but ultimately for elimination. In spite of these three protective organ systems, there can still be danger when taking any medication.


What could possibly go wrong?

Besides the obvious pitfalls of stomach, liver, or kidney disease which may lessen the protective mechanisms of each, drugs can sidestep the organs altogether to create:

Side effects


These are unintended effects occurring at normal doses related to a drug’s pharmacological properties. They are effects other than the ones intended or that go beyond the desired effect.


For example, the drug sildenavil (Viagra), originally derived from a drug to treat low blood pressure (hypotension), can cause hypotension as a side effect.


Adverse events1


An adverse reaction, according to the WHO, is “a response to a drug which is noxious and unintended, and which occurs at doses normally used in man for prophylaxis, diagnosis, or therapy of disease…”2 “Serious” adverse events are adverse events that are life-threatening, require hospitalization, or result in disability.


For example, Viagra, which can effect the chemistry of color perception in the eye (the mechanism of action for erections can crossover with those of color perception), might result in a temporary “blue vision” (cyanopsia) when the vision becomes more sensitive to brightness, especially in the blue-green spectrum. It is usually temporary, but in some cases, visual or auditory deficits become permanent, which would indicate a “serious” adverse event.


Untoward effects


An untoward effect is an unexpected reaction not consistent with the usual information or known characteristics of the drug.3


In the 1950s, the drug thalidomide, used as a sleep-aid during pregnancy, resulted in babies born with limb abnormalities. This was unexpected and tragic, and led to it being discontinued immediately after discovery. Similarly, tetracycline—a popular antibiotic—caused browning discoloration of children’s teeth. Although this was an untoward effect, it was not considered a serious adverse event, so tetracycline is still available, but pregnancy and childhood are listed as contraindications.


Drug-drug interactions4


For example, picking on Viagra once more, it can mix badly with other nitrates used to treat hypotension, causing serious cardiac events. Alcohol, as well, can potentiate its hypotensive tendencies. Taking it with erythromycin, a popular antibiotic, may result in higher levels of the sildenafil in the body.


Allergic reactions


Allergic reactions5 are, in fact, allergies to the medication. These are a result of the immune system. If exposure to a drug, for some reason, provokes an acquired immune response, it could prove life-threatening if given again, since the immune system has been “primed” to attack it, along with some overreaction (allergy). This is why drugs—or drugs in the same class—are avoided if there were ever an allergic reaction (hives, rash, trouble breathing) noted with a prior administration.



These are all different, yet some people think side effects are allergies, more think that adverse events are simply malpractice, and most don’t even know what “untoward effects” are. Nevertheless, they are all sobering consideration when choosing a drug to treat a condition, or in considering whether to treat that condition at all.

Once again, it all comes down to risk vs. benefit. If the risk of an antidepressant is fatigue, this is a better gamble than to risk the possibility of suicide. Statins may cause muscle cramps and damage,6 but getting the cholesterol under control is more likely than the side effects and can save someone from a stroke or heart attack. A life-threatening sepsis (blood infection) can result in hearing loss with certain antibiotics, but the alternative is unacceptable. Steroids can result in gastric bleeding, antifungals and acetaminophen can cause liver damage, and kidney damage can occur with contrast media used in imaging studies. All of these are reasons that a physician must be involved, of course.


In adding up all of the bad reactions of drugs with the good that they do, the “good” side of the spreadsheet is an exponentially longer column. A 99% chance of everything going right dwarfs the < 2% risk of something going wrong. This is especially true if a disease or condition is 100% dangerous. If someone’s a betting man (or woman), the odds are with ‘em, because a physician can stack the deck in their favor.


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Disclaimer: The contents of this article are for informational purposes only and must not be considered as medical advice. YouDrugstore does not endorse or approve the opinions or views expressed by any contributing author in our community articles. Always consult your doctor for medical advice.