Understanding Pharmacology and How Medications work in your body

Taking better care of yourself through increasing your knowledge about healthy living.


Learning About Your Prescription and Non-Prescription  Medications

We all want to know more about medications and how they work. To understand drugs and the specific action they have in your body, here are a few bits of knowledge.


First of all, all drugs are metabolized in the liver, and therefore the liver is the first organ to have problems if drugs accumulate there.

Some drugs  can have effects on your kidneys too. So, even that over-the-counter drug that you took for a headache, can eventually cause you some problems with your internal organs, especially the liver and kidneys.

A doctor may stop a medication if he or she feels that the drug may be causing cumulative ( building up in your body) effects.

This is why doctors  ask you to go for blood work. Blood work interpretation  can help your doctor see if there is any damage to your internal organs, especially if you have to be on medications for extended periods of time.

Here are a few definitions that can increase your knowledge related to medications that you may be taking

Topical: Topical meds are placed or rubbed on the skin, like acne medication. Therefore, they take longer to  get into your body.

Systemic: Systemic meds have more side effects because they go directly into your system through various routes- the mouth, under the skin ( as in an allergy shot, 0r TB test) or directly into the body through an injection. So when you get a shot- you may have reactions or interactions right away because it goes straight through the body systemically.

Dehydration: make sure that you drink enough water when you are on medications because dehydration can cause medications not to work as well. When you take prescription drugs, they need water to work.

How to take your meds: Follow the directions on your prescription meds  very closely

Most  medications  need to be taken with water, but not  with milk ( as in some antibiotics), or not with juices ( as with many drugs) because they may break down the drug before it gets where it needs to.

Synergism: This is a term that means that if you are taking more than one medication, the combination of both may make them more powerful. This can sometimes be good- and sometimes not so good.

Antagonism: This term means that the combination of 2 drugs may antagonize one of them. Meaning that one may not work when the other is added, canceling the effects of both.

Doctors and pharmacists are aware that this can happen ( synergism and antagonism) so today, there are computers that tell the doctors/pharmacist if the drug they are prescribing may interact negatively in some ways. That is why it is so very important to tell your doctor all of the drugs that you may be taking, even the over-the -counter ones that you think may not matter.

Doctors want the  medications that they give you to work the best that they can- this is called efficacy. Efficacy means that a medication is producing the desired effect. And potency means the strength of a medication.


In general, a poor diet can reduce the therapeutic effects of most medications because nutrients are needed for medications to be absorbed.

Special Conditions

Some medications can cross into the brain or into a fetus so pregnancy has to be considered when doctors are prescribing medications Some drugs such as psychotropic and antidepressants can cross into the brain and growing baby. This is called crossing the blood -brain or blood-fetal barrier.

Other special considerations are adverse reactions or harmful side effects.

These 2 definitions mean the same thing. Your doctor has to be very aware, and tell you about the side effects that your specific drug may have.  If you feel that you are having an adverse reaction, call your doctor right away, and stop the medication until you see him or her.

Severe Side Effect from Allergic Reactions to Medications

A severe side effect is call anaphylaxis, and if this happens there are many symptoms that can be life threatening, and in need of a counter reactive drug such as benadryl or epinephrine ( that is why people carry around “epi pens” for allergies to bees.) If a reaction develops, an itchy red rash may develop. This is called urticaria.


Unusual Happenings

Sometimes an unusual or unique reaction happens when a drug is given to a patient. This term is called idiosyncratic. It means that no one else ever had the same symptoms that you had from the particular medication.  An example is that you may get hiccups every time you take a Tylenol!


Ototoxicity is damage to the ear that may be caused by some medications. Some antibiotics can cause ototoxicity, especially the aminoglylcoside class. Specific drugs such as gentamicin and tobramycin may cause  ototoxicity.

Loop Diuretics: Another medication that may cause ototoxicity is the loop diuretic, furosemide or called Lasix, especially if given in high doses.

Taken in part from: Gauwitz, D. (2009). Administering Medications. Pharmacology for Health Careers. 6th ed.  Rochester, Minn. McGraw-Hill