How Medication Works in Your Body

Drugs work in your body in a variety of ways. They can interfere with microorganisms (germs) that invade your body, destroy abnormal cells that cause cancer, replace deficient substances (such as hormones or vitamins), or change the way that cells work in your body.

Pharmacist filling perscriptions
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There are more than 20,000 medications available by prescription, and still more available over the counter. Some can be used to treat several different health conditions. Aspirin, for example, can be used to treat pain, inflammation, and fever. In addition, aspirin can prevent heart attacks if taken on a regular basis.

The following information is a basic overview of how some drugs work to improve your health.

Fighting Infections

An infection occurs when microorganisms, such as bacteria or viruses, invade your body. Medications used to treat infections can kill germs directly or prevent them from multiplying and growing.

Some medications used to treat infections include:

  • Augmentin (amoxicillin/clavulanic acid), used to treat ear infections
  • Bactrim (trimethoprim-sulfamethoxazole), used to treat urinary tract infections
  • Lamisil (terbinafine), used to treat ringworm
  • Pen-Vee K (penicillin), used to treat strep throat
  • Valtrex (valacyclovir), used to treat herpes infections

Targeting Cancer Cells

There are three types of medications used to treat cancer. Chemotherapy attacks cancer cells directly and stops or slows their growth and spread. Biological therapy helps your body’s immune system fight cancer. Lastly, antiangiogenic therapy blocks the growth of new blood vessels to a tumor, which may cut off a tumor's supply of oxygen and nutrients. Some cancers are treated with a combination of these medications.

Some medications used to treat cancer are:

  • Adriamycin (doxorubicin), a chemotherapy agent used to treat a number of cancers, including bone, breast, stomach, lung, bladder, leukemia, and lymphoma
  • Avastin (bevacizumab), an antiangiogenic therapy used to treat cancers of the colon, rectum, or lung
  • Intron-A (interferon alpha), a biological therapy used to treat malignant melanoma
  • Herceptin (trastuzumab), a biological therapy used to treat breast cancer
  • Platinol (cisplatin), a chemotherapy agent used to treat many types of cancer, including bladder, lung, and head and neck

Replacing Missing or Deficient Substances

Your body needs certain levels of amino acids (or proteins), vitamins, and minerals to work properly. If these substances are deficient or missing, you can develop health conditions such as scurvy (vitamin C deficiency), anemia (iron deficiency), and pernicious anemia (vitamin B12 deficiency). Recent medical studies suggest that a lack of vitamin D may increase the risk of heart attack in men. Your healthcare provider, therefore, can order a blood test to measure your vitamin D levels and may recommend a vitamin D supplement.

You also can develop a deficiency disorder caused by a lack of hormones in your body. Hormones regulate many of the functions in your body, and a deficiency in one or more hormones can cause serious health problems. Diabetes (insulin deficiency), hypothyroidism (thyroid hormone deficiency), and short stature (growth hormone deficiency) are some examples.

Some medications used to treat hormone deficiency disorders are:

  • Androgel (testosterone), used to treat hypogonadism (low testosterone in men)
  • Humalog(insulin lispro), used to treat diabetes
  • Humatrope (somatropin), used to treat short stature due to growth hormone deficiency
  • Premarin (conjugated estrogens), used to treat symptoms of menopause
  • Synthroid (levothyroxine), used to treat hypothyroidism

Changing How Cells Work

Most common chronic diseases—such as asthma, type 2 diabetes, hypertension, arthritis, heart disease, and some types of mental illness—are caused by an abnormality in how the cells in your body function. These abnormalities may be caused by aging of cells, genetics, wear and tear on the body, and lifestyle issues such as smoking, lack of exercise, poor eating habits, and environmental stress and pollution.

Most medications prescribed or sold over the counter target one or more of these cell abnormalities. For example, some medications used to treat pain and inflammation interfere with the production of chemical substances that are released by cells in response to tissue damage. These chemical substances, also known as mediators, are responsible for the pain and swelling of arthritis and injuries.

Some medications used to treat depression work by increasing the amount of a chemical messenger in the brain. Additionally, some other medications make cells more or less sensitive to hormones in the body. Beta blockers, such as Tenormin (atenolol) and Toprol XL (metoprolol), are used to treat hypertension by making heart cells less sensitive to the body’s adrenaline.Some oral diabetes medications, such as Actos (pioglitazone) and Avandia (rosiglitazone), make muscle cells more sensitive to insulin.

Some medications that alter the function of body cells are:

  • Arthrotec (diclofenac, misoprostol), used to treat arthritis
  • Lipitor (atorvastatin), used to treat high cholesterol
  • Nexium (esomeprazole), used to treat GERD (heartburn)
  • Viagra (Sildenafil), used to treat erectile dysfunction
  • Zoloft (sertraline), used to treat depression

On a final note, it should be mentioned that the drugs listed in this article can be taken in different ways. For instance, insulin is injected, Augmentin and many other antibiotics are taken by mouth, and Androgel is a testosterone gel.

Here are different ways that drugs are introduced into your body.

  • Taken by mouth (oral)
  • Injection
  • Placed under the tongue (sublingual) or between the gums and cheek (buccal)
  • Inhaled into the lungs
  • Delivered through the skin by a patch (transdermal)
  • Placed in the eye or ear
  • Placed in the rectum or vagina
  • Sprayed in the nose

If you have any questions about how your medications work or how they are taken, call your healthcare provider's office or make an appointment to see him or her. Additionally, your pharmacist is a wonderful resource who can help you better understand your medications.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. US Food and Drug Administration. Fact Sheet: FDA at a Glance. November 2020.

  2. Arruebo M, Vilaboa N, Sáez-gutierrez B, et al. Assessment of the evolution of cancer treatment therapies. Cancers (Basel). 2011;3(3):3279-330. doi:10.3390/cancers3033279

  3. Judd SE, Tangpricha V. Vitamin D deficiency and risk for cardiovascular disease. Am J Med Sci. 2009;338(1):40-4. doi:10.1097/MAJ.0b013e3181aaee91

  4. Wiysonge CS, Bradley HA, Volmink J, Mayosi BM, Opie LH. Beta-blockers for hypertension. Cochrane Database Syst Rev. 2017;1:CD002003. doi: 10.1002/14651858.CD002003.pub5

Additional Reading
  • Drug Administration. Merck Manual. Consumer Version.
  • How Medications Work. Johns Hopkins Prescription Drugs Reports.

By Michael Bihari, MD
Michael Bihari, MD, is a board-certified pediatrician, health educator, and medical writer, and president emeritus of the Community Health Center of Cape Cod.