28 Medical Words to Never, Ever Confuse

These words aren’t interchangeable, and a medical mistake could endanger your health.

Kelsey McArdle/RD.com

What’s the difference between an ER visit and urgent care?

Both sound like they’re meant for an immediate medical condition, but they aren’t for the same types of emergencies. Urgent care centers are designed for similar care to what you’d get from your primary care doctor. If you have a fever, sore throat, vomit, or a shallow cut and can’t make an appointment with your regular physician, head to urgent care. The ER should be reserved for conditions that need quick or advanced treatments that you can only get at a hospital. Difficulty breathing, severe pain in the abdomen or chest, eye or head injuries, and cuts deep enough for stitches should all be treated in an emergency room. These are the secrets urgent care centers won’t tell you.

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What’s the difference between heart attack and sudden cardiac arrest?

When an artery becomes blocked and can’t deliver oxygen-rich blood to the heart, some of the heart’s muscle cells die, causing a heart attack. It could feel like chest pain or pressure, indigestion, or a rapid heartbeat. Sudden cardiac arrest might happen during a heart attack, or it might occur separately. When its electrical system malfunctions, the heart starts beating way too fast, making its chambers quiver and lose ability to deliver blood. You might start to feel dizzy or a racing heartbeat, or no symptoms at all.

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What’s the difference between dementia and Alzheimer’s disease?

Dementia isn’t a specific disease—it’s an umbrella term for a group of symptoms that affect memory and reasoning. Alzheimer’s is just one of the diseases that could be behind the dementia. It’s impossible to diagnose with 100 percent accuracy without an autopsy, but patients have a slow decline in memory and cognitive function.

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What’s the difference between an artery and a vein?

Your arteries deliver oxygen-rich blood from your heart to the rest of your body. Veins then take that blood and return it to the heart for purification.

Kelsey McArdle/RD.com

What’s the difference between inflammatory bowel disease and irritated bowel syndrome?

IBS is a functional disorder rather than a disease, meaning your digestive system isn’t working right but still looks normal, with no identifiable cause for your bloating, cramps, and stool problems. IBD, on the other hand, is more serious and is classified as a disease. Along with the symptoms associated with IBS, IBD can also be marked by ulcers, extreme fatigue, rectal bleeding, and more. Don’t miss these health insurance tricks that could save you thousands of dollars. 

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What’s the difference between osteoarthritis and rheumatoid arthritis?

The cause of your arthritis could result in different symptoms that call for different treatments. Osteoarthritis causes achy joints, but usually no swelling. It usually appears later in life, when the joints have been worn down from repetitive use. Rheumatoid arthritis is a much less common disease in which the immune system attacks the joints. It’s marked by pain, swelling, and fatigue.

Kelsey McArdle/RD.com

What’s the difference between an electrocardiogram and an echocardiogram?

Both are noninvasive tests used to help identify heart problems. An electrocardiogram (EKG) represents the organ’s electrical activity as wavy lines on a piece of paper. Your doctor might use it to check muscle and tissue damage, heartbeat irregularities, or chemical imbalances. An echocardiogram (echo) is an ultrasound that creates a moving picture of your heart pumping to look for tumors, blood clots, infections, and more.

Kelsey McArdle/RD.com

What’s the difference between acid reflux, heartburn, and GERD?

When acid splashes out of the stomach and into the esophagus, acid reflux occurs. Heartburn is the sensation you feel in your chest when that happens. Severe or chronic acid reflux becomes gastroesophageal reflux disease, which can lead to serious complications like ulcers or cancer. Check out these common medical abbreviations you should know by now.

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What’s the difference between mucous, mucus, and phlegm?

Mucus is the slimy fluid that you’ll find in your nose and sinuses, while mucous is an adjective, as in the mucous membranes that secrete mucus in your gut and respiratory passages. The mucus captures dirt and dust before they can get to your lungs, and a runny nose is usually a mix of mucus and watery secretions. On the other hand, phlegm is produced in the lower airways, and you’ll notice it if you have a loose cough. These are the health perks you didn’t know you could get for free.

Kelsey McArdle/RD.com

What’s the difference between blood pressure and heart rate?

Blood pressure is the force against your artery walls from the blood pumping through your body. A measurement includes systolic pressure (the top number), representing the pressure as your heart is forcing the blood out during a heartbeat, and diastolic pressure (bottom number), or the pressure while your heart is relaxed between beats. Heart rate refers to the number of times your heart beats every minute, represented in a single number. A faster heartbeat doesn’t mean higher blood pressure.

Kelsey McArdle/RD.com

What’s the difference between celiac disease, gluten sensitivity, and wheat allergy?

Celiac disease is an autoimmune disorder affecting about 1 percent of people. When people with celiac eat gluten, a protein found in wheat, barley, and rye, their immune systems attack their small intestines and cause inflammation. Non-celiac gluten sensitivity hasn’t been studied widely, but some people who aren’t diagnosed with celiac disease find that symptoms like bloating, gas, abdominal pain, headaches, and numbness go away after they stop eating gluten. A wheat allergy has to do with the wheat protein itself, meaning gluten from other sources can be eaten without any reaction.

Kelsey McArdle/RD.com

What’s the difference between an aneurysm and stroke?

Aneurysms in the brain are weak, bulging areas in the artery walls that don’t typically cause symptoms. If the aneurysm breaks, though, blood will get into the skull, causing a stroke when the brain doesn’t get the blood it needs. A stroke can also happen if a blocked artery prevents blood from reaching the brain.

Kelsey McArdle/RD.com

What’s the difference between a hangnail and an ingrown nail?

A hangnail isn’t actually part of your nail—it’s a piece of skin that detaches from the side of your cuticle. You can treat it by snipping it off with clean cuticle scissors. An ingrown nail, on the other hand, develops when the side of your nail burrows into your skin instead of growing over it. Ingrowns usually affect toenails and can result from nails cut short and curved instead of straight, shoes that don’t fit, and injuries. You shouldn’t cut the ingrown portion by yourself, so see a doctor if the condition doesn’t get better to avoid risk of infection or more pain.

Kelsey McArdle/RD.com

What’s the difference between type 1 diabetes and type 2 diabetes?

About 5 to 10 percent of people with diabetes have type 1. Their immune systems destroy insulin-releasing cells, meaning the body eventually has no insulin. The disease usually develops in childhood, and those with type 1 diabetes often have low blood sugar. Type 2 diabetes, on the other hand, usually develops later in life and could be delayed or prevented with a healthy diet and exercise. The bodies of those with type 2 diabetes still release insulin, but they can’t use it correctly. As the disease gets worse, the pancreas might start producing less insulin, leading to a deficiency. Here are tips for surviving your next hospital visit. 

Kelsey McArdle/RD.com

What’s the difference between mold and mildew?

These are both types of fungi that you might find in your home, especially moist areas like bathrooms and basements. Mildew is usually gray or white, flat, and musty-smelling, while molds are darker and can even be hairy. Mildew might cause minor health issues like occasional coughing, but mold can lead to serious long-term respiratory problems. Use a solution of ¾ cup bleach and 1 gallon of warm water to attack mildew or light mold, but leave heavy infestations to a professional. Here are the secrets nurses wish they could tell you. 

Kelsey McArdle/RD.com

What’s the difference between acne and rosacea?

When hormones cause the skin to get extra oily, you might end up with an acne breakout, even as an adult. Rosacea can look like pimples but is a chronic inflammatory disease. In addition to the bumps, people with rosacea also commonly have red cheeks or noses, and facial swelling. Acne medications might cause their skin to react instead of calming it down.

Kelsey McArdle/RD.com

What’s the difference between survival rate and relative survival rate?

A survival rate calculates the number of people who survive a specified cause of death, while leaving out those who had that disease but died of another cause. Relative survival rate, on the other hand, is the ratio of those who have that disease and survive (regardless of cause of death) to those who survive in the general population. So a five-year relative survival rate for breast cancer refers to how likely that person is to survive compared to a cancer-free individual. Look out for these silent signs your body is in trouble.

Kelsey McArdle/RD.com

What’s the difference between drug misuse and abuse?

Using more than the recommended dose of a drug but still seeking the medical effects is misuse. For instance, a person might pop an extra sleeping pill if the first one isn’t working, or give a prescribed medication to a friend complaining of similar symptoms. Abuse, on the other hand, refers to taking the drug (especially at a high dose) with the goal of getting high. Regardless of intention, though, both misuse and abuse can threaten your health, or even your life, so stick to the dosage your doctor recommends, and ask a physician before starting any new medications.

Kelsey McArdle/RD.com

What’s the difference between diverticulosis and diverticulitis?

When gas, liquid, or waste put pressure on the walls of the intestine, little pockets called diverticula might form in a symptom-free condition called diverticulosis. When those pockets get infected and inflamed, diverticulitis occurs. It is more serious, and could cause cramps, diarrhea, constipation, and fever.

Kelsey McArdle/RD.com

What’s the difference between dysphagia, dysphasia, and dysplasia?

Dysphagia is when it’s hard or impossible to swallow. If this happens rarely, like when you eat too fast or don’t chew your food enough, there’s probably no reason to worry. But if the feeling won’t go away, seek medical attention. Dysphasia is a disorder that develops when a brain injury makes it hard to understand written or spoken words. Meanwhile, dysplasia refers to abnormal development of cells, tissue, an organ, or bone.

Kelsey McArdle/RD.com

What’s the difference between podiatrist and orthopedist?

Podiatrists have a DPM degree, which specializes them in treating foot and ankle conditions. An orthopedic surgeon is an MD or DO qualified to treat the whole musculoskeletal system, including (but not limited to) foot and ankle problems. For foot or ankle pain caused by lower back, knee, or hip problems, an orthopedist might be the better bet.

Kelsey McArdle/RD.com

What’s the difference between hypertension and hypotension?

Whether too high or too low, the pressure of your blood against your artery walls can cause side effects. Hypertension, or high blood pressure, can lead to stroke, heart disease, kidney failure, and more. Hypotension, or low blood pressure, usually won’t cause problems, but a sudden drop could make you feel dizzy, faint, or go into shock.

Kelsey McArdle/RD.com

What’s the difference between hepatitis A, hepatitis B, and hepatitis C?

They might share similar names, but three different viruses cause these inflammatory diseases. The symptoms are usually the same: fever, nausea, vomiting, yellowing skin, joint pain, fatigue, and gray stool. But hepatitis A is spread when microscopic amounts of contaminated fecal matter are ingested, while hepatitis B is spread through bodily fluids like blood or semen, and hepatitis C is only spread through blood. The CDC recommends all children and babies get vaccinated for hepatitis A and B, but there’s no vaccine for hepatitis C. Don’t miss these medical tips that doctors and nurses wish you knew.

Kelsey McArdle/RD.com

What’s the differene between sex and gender?

You might use the terms interchangeably, but these terms have different meanings. Sex refers to biological differences between men and women. Gender, on the other hand, deals with the social differences between male, female, and other gender identities.

Kelsey McArdle/RD.com

What’s the difference between psoriasis and eczema?

Both skin conditions can cause itchy, scaly, red rashes on the hands, feet, and neck. Psoriasis might also occur on the elbows or knees, and the red patches are covered with silvery scales. Eczema, or atopic dermatitis, usually develops before age five and is often found on the backs of the knees or insides of the arms. Small, pimple-like bumps that might ooze or crust over set it apart from psoriasis.

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What’s the difference between a fracture, a sprain, and a strain?

A fracture is just another word for a broken bone, no matter how severe. Sprains, meanwhile, aren’t bone-related—they occur when the ligaments that keep your bones in place are torn from being twisted or stretched too far. Strains happen when overstretching damages muscles or the tendons connecting muscle to bone.

What’s the difference between aural and oral?

Kelsey McArdle/RD.comThey may sound the same, but these words have totally different meanings. Aural refers to the ear or hearing, while oral has to do with the mouth or speaking. (And for the record, oral is said out loud, while verbal can be spoken or written.)

Kelsey McArdle/RD.com

What’s the difference between palpation and palpitation?

The method health care providers use when examining a body part with their fingers or hands is called palpation. On a different note, a palpitation is when you feel like your heart is fluttering, beating too hard, or skipping a beat. They’re typically caused by stress, caffeine, alcohol, or nicotine and aren’t a reason for concern, but some could be caused by heart disease or another medical condition. Next, brush up on these medical terms you always mispronounce.

Marissa Laliberte
Marissa Laliberte-Simonian is a London-based associate editor with the global promotions team at WebMD’s Medscape.com and was previously a staff writer for Reader's Digest. Her work has also appeared in Business Insider, Parents magazine, CreakyJoints, and the Baltimore Sun. You can find her on Instagram @marissasimonian.