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What Is the Difference between Drug Allergy and Drug Side Effect?

Why do we need to take drugs? Why do we take them? To get rid of some hard to tolerate condition or uncomfortable symptoms or to get relieve from some illness. Drugs in most cases treat symptoms, not the cause of illness, but who cares, if you just need a quick result and go on working or living your life…

But along with desired effect drugs can cause some other effects, which “politically correct” are called side effects and drug allergies. All drugs have this black list of potentially possible side effects (which may or may not occur, depending on plenty of reasons); you can always see it on drug label of each taken medication. Drug allergy is less common, needs special identification and other special recommendation. So, how can we cross the line between these two cases? Let’s try to find some differences between them.

Side effects

Side effects (or adverse effects) are unwanted negative consequences that you experience while taking the medication or after it.

Every label of any medication has ‘side effects’ section. You take something to relieve one symptom, and you may get some other unwanted symptoms in other part of your body. The list of adverse effects in the label can be rather big and serious. It doesn’t mean that you will have all of them, in fact, you may have none. But manufacturers should list all of the possible side effect of your body to the ingredients and chemicals in medication you take. There are several side effects types:

- so-called ‘mild’ side effects, which you can easily tolerate;

- ‘mild’ effects that can be tolerated, but are unpleasant (the desired effect is much higher than the uncomfortable feeling from adverse effect of the drug);

-  potentially harmful side effects that may itself require treatment;

-  severe side effects that prone you immediately to stop taking the drug.

Some medication may cause adverse effects only after some time of using it, in case of higher dose (or overdosing) or only after combining the medication with some other drugs.

Among the example of mild side effects the following can be listed:

-  Nausea

- More serious digestive problems - vomiting, diarrhea

-  Muscle aches

-  Headaches, migraines

-  Fatigue

-  Insomnia

-  some others

The lists of most common more or less severe side effects are:

-  Confusion

-  Muscle deterioration

-  Kidney / liver damage

-  Bleedings

-  All the list of mild effects if they are severe (severe headaches, severe muscle aches, etc.)

Different people may have different adverse effects from the same drug. All these side effects occur differently from person to person depending on genetic factor, on the nature (and the state) of the disease (or condition) and on some other various reasons (such as taking other drug or patient lifestyle). 

Drug allergy

Drug allergy is an unwanted adverse effect from taking the medication (try not to get confused after reading the definition, as the difference will be clear lower in the article).

If you have side effects after taking a drug it doesn’t mean you are allergic to that drug (or its main ingredient). Drug allergy differs from just having side effects from taking a drug. First of all, it includes different symptoms. Among typical symptoms of drug allergy there are:

1.Mild symptoms:

  • Rash
  • Itching
  • Hives
  • Fever

2. Moderate symptoms:

  • Facial swelling (of the upper throat)
  • Difficulty in breathing
  • Falling of blood pressure (very often to dangerously low levels)
  • Irregular heartbeat

3. Delayed drug allergy that occur usually after 7 to 21 days of taking the medication (very often vaccine). It is also called serum sickness. Includes:

  • Different inflammation processes

4.  Anaphylaxis – a sudden, often life-threatening extremely severe allergic reaction that involves the whole body. Symptoms includes:

  • Irregular heartbeat
  • Rapid decrease of blood pressure
  • Rapid or weak pulse
  • Difficulty breathing (swelling of the upper throat)
  • Face color changes (to blue, including lips and nails; or to red with itching and hives)
  • Confusion
  • Fainting
  • Abdominal cramps
  • Nausea, vomiting, diarrhea

Different medications can cause drug allergy symptoms of any type (depending on the same plenty of factors as with side effects, plus the fact of the first exposure to that medication). But among all the drugs there are groups of medications that cause allergy more often than others:

-   Antibiotics (especially penicillins - Penicillin, Ampicillin, Amoxil; cephalosporins - Keflex, Cefzil, Vantin, etc.  and sulphonamides -  Bactrim, Septra, etc.

-  Aspirin-like drugs (NSAIDs) (especially ibuprofen and indomethacin)

- Blood pressure medications (ACE inhibitors, Beta-blockers, Calcium channel blockers, etc.)

-  Antiepileptic drugs (such as Dilantin, Depakene, Tegretol)

-  Insulin (Pork and beef)

What makes drug allergy differ from state when you experience drug side effect:

1. Drug allergy is an immune response of the body to the taken medication. This is the main difference! Side effects do not involve the immune system of the patient.

2. It is a rather rare state.

3. Drug allergy can occur with any dose of medication (in case of side effects – they usually occur at higher dose or at overdosing).

4. Drug allergy can begin at any time of taking medication - within only several minutes of taking the first dose, or after some time (and days) of using it (with side effects - they usually occur after some time of taking the drug).

5. Drug allergy can be life threatening.

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What is the answer?

In case with side effects, it is very important to use the medication as your doctor proscribes you (follow the dosage and the exact time of taking it (for example, every 4 hours, or 6, 12 hours) and the period of time you take it (7 days, or one month, etc.). It is also important to follow the label and do not take the drug if you have some conditions that may increase the risk of having side effects (they are also listed in the label, for example, if you have a liver disorder or diabetes, or you are over 60 years of old, etc.).

In case of drug allergy, as far as you (or better your doctor) identify it, it is extremely important to remember the medication (that causes you an allergy) and always tell your doctor (or pharmacist) about it before any prescriptions. After all, a qualified doctor can always try to find you best suitable option even if you have these two different types of conditions.

Valentyna Ant.

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