Medical Terms A to Z: Common and Confusing Terms Used in the Doctor’s Office

If you've ever gone to a doctor's appointment and left feeling more confused than before, you're not alone. Only a third of Americans feel comfortable on measures of health literacy, such as following a doctor's instructions or the directions on a prescription label.

We put together an A to Z glossary of common medical terms you might hear from your doctor or in medical information as you navigate living with a chronic illness, including terms related to clinical trial participation. And of course, don't ever hesitate to ask for clarification if you need it any time you talk with your doctor.

If there are confusing words you've heard that you don't see here, let us know and we will add them!


Acute: Sudden start of symptoms.

  • Strep throat is an acute illness because it comes on quickly.

Aggravate: Make worse

  • Being out in the sun aggravates Holly's lupus symptoms.

Anemia: Low red blood cell count. Being anemic can make you feel tired and weak.

  • Exercise can be difficult when you have anemia and feel tired.

Antibiotics: Drugs that either kill or stop the growth of bacteria.

  • Chris took antibiotics to treat an infection.

Anti-inflammatory: A medicine that reduces pain and swelling.

  • Jill takes an anti-inflammatory for her arthritis symptoms.

Asymptomatic: Not showing symptoms, but being sick.

  • The early stages of breast cancer can be asymptomatic.

Autoimmune disease: A disease that makes your immune system attack your own body.

  • Celiac is an autoimmune disease that causes a reaction to eating gluten.


Benign: Not a danger

  • Jackie was relieved to find out that her tumor was benign.


Chronic: Does not go away or lasts a long time.

  • HIV/AIDS is a chronic disease; it does not go away.

Clinical study: Studies in a medical setting that involve patients.

  • Ronda is in a clinical study for a new rheumatoid arthritis treatment.

Clinical trial: A study that tests a potential new medication or medical device for safety and effectiveness.

  • All medications in the U.S. must go through clinical trials before patients can buy them.

Condition: A disease or medical problem.

  • Clinical trials look for volunteers living with a certain condition as well as healthy volunteers.

Cutaneous: About the skin

  • Lupus can have cutaneous symptoms that appear on different parts of the body.

Convalescence: Time spent recovering from an illness.

  • After Holly broke her hip, she had a long period of convalescence.



Degenerative: Causing more damage over time.

  • Alzheimer’s is a degenerative disease that causes memory loss over time.

Deteriorate: Breaking down, getting worse

  • Liz uses hearing aids now because her hearing has deteriorated.

Dose: An amount of medicine.

  • Julie’s doctor told her to take the correct dose of the medicine he prescribed.


Effective: Something that works.

  • Sam found an effective treatment for his rheumatoid arthritis.

Exert: To put in effort

  • Rob’s physical therapist told him to exert himself when riding his stationary bike.


Fast: To go without any food or drink for a period of time.

  • Pete had to fast for a day before his procedure.

Fatigue: A strong tired feeling that goes beyond just sleepiness.

  • When Sally feels fatigued, she feels tired in her whole body.


Gradually: Slowly, over time

  • Gloria's flu symptoms gradually got better over the course of the week.

Glucose: Refers to blood sugar

  • Greg needs to check his glucose levels often because he has diabetes.


Hallucinate: See things that are not there

  • Harry had an episode and started hallucinating.

High risk: There's a good chance something will happen

  • He is at high risk for sunburn because he is so fair.

Hypersensitivity: Getting a strong reaction to something.

  • She gets bad sunburns because of her hypersensitivity to sunlight.



Idiopathic: Arising from an unknown cause

  • Most cases of Parkinson's disease are idiopathic; the cause is unknown.

Immune System: The part of the body that fights against germs and infections

  • Getting enough sleep and eating a healthy diet can help your immune system.

Inflammation: Swelling, redness, heat, and pain that happens when parts of the body are hurt or react to an illness. The symptoms are caused by the body sending extra blood cells to the place that is hurt.

  • Rheumatoid arthritis causes inflammation in the joints.

Inhibit: Prevent

  • Using a special lotion inhibited the spread of Jose's rash.

Intravenous: Through a vein, such as putting fluids or medicine into a vein using a needle.

  • Alicia received her medication intravenously from a nurse.


Localized: In a small area

  • The rash was localized to Annemarie's face.

Long-term: A period of time longer than a few weeks or months

  • After her hip replacement, Donna spent time in long-term care.


Malignant: Invasive; a malignant tumor grows uncontrollably and spreads to other parts of the body

  • Lorie was relieved that her tumor was not malignant.

Manage: Control, take care of

  • Shirley's doctor gave her recipes to help her manage her diabetes.

Moderate: Between weak and strong

  • Charles told his doctor that he was feeling better but still had moderate pain.

Monitor: To watch carefully for changes

  • After her knee surgery, Lily's recovery was closely monitored.


Narcotic: A strong medicine used to treat pain. Narcotics can make you sleepy and can be addictive.

  • You shouldn't drive while taking a narcotic or you may fall asleep at the wheel.

Negative: In medicine, a negative result means that something is not there.

  • Holly's tests came back negative for pneumonia.

Neurologic: Having to do with the nervous system.

  • Alzheimer's is a neurologic disease that causes memory loss.


Observe: To watch

  • Adria's surgery was successful, but her doctor wanted to observe her for a few days.

Occasionally: Sometimes

  • Nancy's eczema was mostly cleared up, but she occasionally still has symptoms.

Occupational therapist: A healthcare professional who helps you learn how to do everyday tasks at home or at work after a surgery or medical diagnosis

  • John saw an occupational therapist for help at work after his Parkinson's diagnosis.

On an empty stomach: Without eating; typically used when describing whether or not to eat or drink before taking a certain medication

  • The doctor told Harold to take the medication on an empty stomach before breakfast.

Oral medication: Medication that you swallow

  • Maria takes an oral medication for her asthma as well as an inhaler.



Paramount: Most important

  • It was paramount that Julia take the medication on an empty stomach, or it wouldn't work as well.

Permanent: Never goes away

  • Alice went to the dentist and got a permanent new tooth.

Pertinent: Important

  • It was pertinent that Jacob take the antibiotic twice a day.

Physical therapist: Someone who works with you to improve pain and build strength

  • After his knee replacement, John worked with a physical therapist for a few months to build his strength.

Placebo: In clinical trials, a substance that has no effect, using for testing purposes.

  • Not all clinical trials use placebos.

Positive: In medicine, positive means that a test was done and a disease was detected

  • Tiffany's test came back positive for pneumonia.

Prescription: A doctor's recommendation for a certain medication, also known as Rx or “script”

  • Todd's doctor wrote him a prescription for an antibiotic.

Prevent: To stop from happening

  • Regular exercise and healthy eating can help prevent heart disease.

Progression: In medicine, getting worse over time

  • There are a few different stages of disease progression for multiple sclerosis.


Quarantine: To be separated in order to stop the spread of an infection

  • When she got sick, Janet was quarantined in the hospital to prevent other patients from getting sick, too.


Reaction: Response

  • Ken had an upset stomach in reaction to a new medication he was taking.

Regular: Happening on a schedule

  • Regular exercise can help you stay healthy.

Relief: Feeling better

  • The painkiller gave Joan some relief.

Remission: A period of time when disease is not active

  • Annie threw a party when her cancer went into remission.

Research study: Tests for a potential new treatment


Sensitive: Easily hurt; reacting easily

  • Susan used a special lotion for her sensitive skin.

Severe: Very bad

  • Taking certain medications on an empty stomach can cause severe stomach problems.

Side effect: A reaction caused by a medication that sometimes can make you feel worse

  • Certain steroids can cause weight gain as a side effect.

Sign: A medical problem noticed by a doctor

  • Ralph had signs of arthritis in his knees.

Stamina: Endurance

  • Since Stella's hip replacement, she's found that she doesn't have the same stamina for exercise that she used to.

Steroids: Medications that are used to reduce inflammation

  • Steroids can help treat pain in conditions like lupus.

Supplement: To add on

  • Taking vitamins can supplement a healthy diet.

Suppress: To hold back

  • Steroids can suppress an overactive immune system.


Taper: To reduce over time

  • Kevin's doctor tapered him off the painkiller he was taking.

Temporary: For a short time

  • Amanda's dentist told her that the swelling in mouth after her tooth was removed would only be temporary.

Therapy: A treatment

  • Clinical trials explore potential new therapies for different conditions.

Treatment: Something given to a sick person to make disease symptoms better

  • Nate's doctor worked with him on his diabetes treatment plan.

Trigger: A cause


Unnecessary: Not needed or important

  • Cynthia's doctor wanted to make sure she didn't get an unnecessary surgery.


Vague: Unclear

  • Steve felt like his doctor's instructions were vague, so he asked him a few follow-up questions.

Voluntary: Choosing to do something on your own

  • Participating in clinical trials is completely voluntary.


Warning sign: Signals that alert you something might be wrong

  • A sore throat can be a warning sign of a cold.

Wheeze: A whistling sound when inhaling and exhaling

  • Liz's asthma can cause wheezing.