30 Signs of Deadly Health Conditions Hiding in Plain Sight

If you start experiencing these signs out of nowhere, don't just brush them off and move on.

When we think of deadly health conditions like cancer and heart disease, it's easy to assume that they are always characterized by obvious symptoms that are impossible to ignore. But the fact is, many signs of serious health conditions hide in plain sight and we tend to chalk them up to stress, aging, or just an inconvenient but harmless health issue.

If you notice unexplained changes in your body, it's always better to be safe than sorry and get yourself checked out. Hopefully there's a simple explanation and solution for those headaches or that fatigue—but if not, going to the doctor as soon as possible could save your life. And for more hints of health problems you should be aware of, check out 40 Subtle Signs Your Body Is Telling You Something's Seriously Wrong.

Panic attacks and stress

Woman with children experiencing anxiety and stress at home

For reasons ranging from stigma to insurance red tape, 56 percent of Americans with a mental health condition such as panic attacks don't receive treatment, according to Mental Health America. Not only is this dangerous to one's mental wellness, it's a potential physical risk as well, since panic attacks and other stress-related issues can actually be signs of heart problems.

"Although chest pain and a tightening sensation are the common and obvious symptoms of coronary artery disease, there can be less obvious symptoms," explains Carolyn Dean, MD, a heart health specialist and author of The Magnesium Miracle. Among these less obvious symptoms are panic, anxiety, and stress, all of which can cause chest pain that you may not recognize as heart-related and therefore may not treat with urgency. And for more on how you are preventing yourself from maintaining a healthy state of mind, check out 26 Things You're Doing That Are Hurting Your Mental Health.

Shortness of breath

Girl at home can't breahe

Most of us experience shortness of breath at least once in a while—and while it's usually harmless, it's also potentially a sign of heart problems cropping up

"The most common symptoms of heart failure include shortness of breath, particularly upon exertion," says Andrew T. Darlington, DO, a practicing physician specializing in advanced heart failure at the Piedmont Heart Institute in the greater Atlanta area. Fatigue and exercise intolerance are also signs of this serious health condition.

Frequent heartburn

Man experiencing pain in heart

Heartburn is fairly common and not generally viewed as a serious health issue, but it can certainly be a sign of one. If you experience persistent heartburn, it could be a symptom of a condition called Barrett's esophagus, according to The Dana-Farber Cancer Institute. People with Barrett's esophagus are at an increased risk of developing esophageal cancer, so it's important to get your heartburn checked out by a professional. And to learn more about how your midsection can alert you to similar health issues, check out This Is Everything Your Stomach Is Trying to Tell You About Your Health.

Chest pain

Male patient wearing face mask and feeling chest pain while being at the hospital during coronavirus epidemic. Healthcare worker is in the background.

Yes, chest pain is the hallmark symptom of a heart attack. But it can also be caused by less serious issues like indigestion and acid reflux. It's important to know that, although some heart attacks are sudden, the majority begin with mild pain or discomfort that may come and go, as outlined by The American Heart Association. So if you experience chest pain, don't take any chances—getting to the hospital immediately could save your life.


Why We Hiccup

For women, the symptoms of a stroke are often subtle—and one of them is hiccups, according to cardiologist Stephen Sinatra, MD. Of course, there's no need to panic about hiccups alone—but if you experience other symptoms such as facial pain, shortness of breath, nausea, and generalized weakness, it's time to go to the doctor. And for things that are putting you in danger of experiencing this serious medical condition, check out 17 Surprising Habits That Increase Your Risk of a Stroke.

Persistent headaches

a woman with gray hair is experiencing a headache

According to the World Health Organization, nearly half of adults experience headaches; so it's no surprise that they're able to hide in plain sight even when they're a symptom of a more serious problem, like a stroke. According to 2015 research published in The Caspian Journal of Internal Medicine, persistent headaches—especially when they're accompanied by vomiting, nausea, and visual changes—could be a warning sign that a stroke is imminent.

Or particularly bad headaches

Woman suffering from terrible headache massaging temples

A headache can also be a sign of meningitis, an infection of the membranes covering the brain and spinal cord. In fact, in one oft-cited 1995 study published in the journal Headache, every meningitis patient who participated reported experiencing a headache, and over half said it was either abrupt onset pain or the worst headache of their life. If your head pain is accompanied by a high fever, it's especially essential to seek medical treatment. If it is meningitis, lack of treatment could lead to permanent neurological damage or even death. And for more another disease that often causes headaches, check out These Are the 51 Most Common COVID Symptoms You Could Have.

A stiff neck

Woman with neck pain

Neck pains and aches can be caused by the flu or other harmless viruses, but extreme neck pain should be taken seriously as it could be another sign of meningitis. In the case of this potentially deadly condition, the pain makes lowering your chin to your chest difficult or impossible, according to healthcare resource Merck Manuals.



This symptom is frequently ignored by both doctors and patients, mainly because some people are just naturally prone to stumbles. But Anthony Kouri, MD, an orthopedic surgeon at the University of Toledo Medical Center, cautions that it can be a sign of something much worse: amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease.

"ALS is a progressive nervous system disease that destroys motor neuron cells and leads to worsening disability and death," Kouri says. "Early symptoms may include tripping or bumping into things, clumsiness or hand weakness, difficulty holding small objects, and muscle cramps or twitching."

Redness on your arms or legs

Woman Scratching a Rash on Her Arm {Allergy Symptoms}

If you notice pain or tenderness around a red area, typically on your leg or arm, Kouri says it's worth visiting the doctor because this could be a sign of necrotizing fasciitis, a rare but deadly bacterial infection that attacks the skin, the fat beneath the skin, and the fascia overlying the muscle.

"It may develop from a small cut, a surgical site, a bruise, a boil, an injection site, or from a small injury from a normal daily occurrence," Kouri explains. "There are several conditions that have the same signs and symptoms as necrotizing fasciitis in the early stages. This is a very difficult diagnosis to make, even for experienced clinicians." That said, if you have all the signs of this potentially fatal infection, be sure to mention it to your doctor. And for more helpful information, sign up for our daily newsletter.

Pigmentation of the palms

parkinsons disease hands

Pigmentation of the palms of the hands is a sign of Addison's disease, a life-threatening illness that occurs when your body doesn't produce enough of certain hormones, explains Laurence Gerlis, MD, CEO and founder of Same Day Doctor in the U.K. "[When a person has Addison's disease,] the adrenal glands fail so the pituitary works harder and produces melanin, which causes pigmentation," he says.

Double vision

Man gets vision exam

Christopher Zoumalan, MD, a board-certified oculoplastic surgeon in Beverly Hills, California, says newly onset double vision and a droopy eyelid "can sometimes be the [sign] of a brain aneurysm." So if you're seeing double, you should be evaluated immediately by a doctor ASAP.


woman sick in bed coughing

Chronic obstructive pulmonary disease (COPD) is a group of lung diseases that are difficult to detect early on. In fact, coughing—along with tightness in the chest and breathlessness—often develop before diagnosis, according to the COPD Foundation. If you begin to experience unexplained coughing that doesn't go away, schedule an appointment with your doctor.


Man Having Trouble Breathing, health risks after 40

Wheezing is often the result of asthma and allergies, but once you've ruled those out, it's time to consider the more serious causes. According to the CDC, wheezing can be a symptom of lung cancer, and Merck Manuals notes that it can be a sign of COPD as well.

Abdominal pain

man on couch with stomach pain, stomach symptoms

Sudden or severe abdominal pain can be a sign of an abdominal aortic aneurysm, according to 2016 research published in The Journal of the American Academy of PAs. Per the CDC, these balloon-like bulges were the primary cause of nearly 10,000 deaths in the United States in 2014, so don't ignore any intense abdominal pain you experience.

Small red bumps or pimples

Woman looking at the red inflamed skin on her arm

Methicillin-resistant Staphylococcus aureus is a particular type of Staphylococcus bacteria that, when it infects the skin, is especially hard to treat. What's worse is that the first signs of an infection are small red bumps or pimples, neither of which raise particular concern for most of us. However, if the infection isn't treated, it can cause infections in the organs and, in some cases, death, so try to be hyperaware of any marks on your skin.



No symptom hides in plain sight more effectively than fatigue. That's why you need to trust your instincts when it comes to this symptom. If you consistently feel unrefreshed after getting eight hours of sleep or you're so exhausted it's nearly impossible to function, it could be a symptom of deadly illnesses like cancer, diabetes, or heart disease. Want to know more symptoms you should inquire about at your next doctor's visit?

Frequent urination


Constantly needing to use the bathroom is certainly an inconvenience, but it's not something everyone feels the need to address with their doctor. However, they should, seeing as frequent urination could be a sign of diabetes, the seventh leading cause of death in America, the American Diabetes Association notes.

If left untreated, diabetes can lead to multiple organ issues including problems with nerves, kidneys, blood vessels, and infections. So if you have to pee more than normal, bring it up to your doctor before it's too late.

Bad breath

Shot of a handsome young man smelling his breath during his morning grooming routine

Bad breath is certainly unpleasant, but it's often chalked up to having a little too much garlic at dinner or a reminder that we need to be more vigilant about oral hygiene. However, Rhonda Kalasho, DDS, a double-board-certified dentist in Los Angeles, California, says it can also be one of the signs of serious health conditions.

"Foul-smelling breath that doesn't go away even after you brush and floss could be caused by things like diabetes, liver disease, and kidney disease," Kalasho explains. "Be sure to visit your dentist to rule out any serious causes."

Metallic taste in your mouth

Man With Weird Taste in His Mouth Signs of Serious health conditions

Here's a scary statistic: 90 percent of adults with kidney disease don't know they have it, according to the Centers for Disease Control and Prevention (CDC). That's because "symptoms of kidney disease can be subtle and easy to ignore," says George Aronoff, MD, vice president of clinical affairs at DaVita Kidney Care, which has multiple locations throughout the U.S.

So what should you look out for as far as subtle symptoms go? "Ammonia breath or an ammonia or metal taste in [the] mouth," according to Aronoff. He notes that waste build-up in the body can also cause changes in taste.


Older Woman with Swollen Ankles {Heart Disease Symptoms}

When the kidneys are working properly, they remove excess water from the body. But when they aren't able to do their job, that fluid stays in your system with nowhere to go. "Fluid the kidneys can't remove may stay in the tissues," Aronoff explains, which is why another sign of kidney disease is swelling of the feet, ankles, hands, or face.

Frank's sign

old man photographed from behind, focus is on ear

Although not everyone with Frank's sign, a crease that appears on the earlobe, has a deadly illness, it's certainly worth a visit to the doctor if you have one. This crease "correlates with coronary artery disease, peripheral vascular disease, and cerebrovascular disease," says Edna Ma, MD, a board-certified anesthesiologist in Los Angeles, California.

New marks on your skin

skin spot on old woman's face, health questions after 40

For those of us who frequently get freckles and moles, a new mark on the skin doesn't always ring alarm bells. But Michelle Lee, MD, a plastic surgeon in Beverly Hills, California, warns that those marks could be melanoma, a rising cause of death.

"Signs of melanoma are the ABCD's: asymmetric border; border edge isn't smooth; color is uneven; diameter is larger than a pencil eraser; and it's evolving in size shape or texture," Lee explains. "When caught early, melanomas are curable—but when caught late, they are the number one cause of death among skin cancers."

Night sweats

sweating in bed

Night sweats have myriad causes, the majority of which aren't life-threatening. But they can also be a sign of cancer, according to Jack Springer, MD, assistant professor of emergency medicine at the Zucker School of Medicine at Hofstra/Northwell in New Hyde Park, New York.

Specifically, The Dana-Farber Cancer Institute notes that night sweats can be a sign of lymphoma and leukemia, both of which require immediate treatment.

Bruising or bleeding easily

white doctor bandaging the hand of an older white woman

Some people naturally bruise more easily than others, but if you notice that you've suddenly begun to bruise like a peach, it could also be a sign of leukemia.

According to the Cleveland Clinic, leukemia patients get bruises from very minor bumps, plus they may bleed from their gums and noses. In the early stages of leukemia, there are often no obvious symptoms so it's important to immediately see a doctor if any signs like these emerge.

Difficulty swallowing

Man is Having Trouble Swallowing

If you have a sore throat from a cold or strep throat, trouble swallowing is par for the course. But if you're not sick, it could be a sign of esophageal cancer, according to The Sidney Kimmel Comprehensive Cancer Center at Johns Hopkins Medicine. And if this is your only symptom, don't let it deter you from seeking medical attention; in the majority of cases, the more serious symptoms don't emerge until the cancer has reached an advanced stage.

Unintentional weight loss


You haven't changed your diet or exercise regimen, but your clothes feel loose and the number on the scale has dropped. It may feel like your lucky day, but unintentionally losing 10 or more pounds is cause for concern. According to The American Cancer Society, unexplained weight loss is one of the first signs of cancer—particularly cancers of the stomach, lung, esophagus, and pancreas.


Cropped shot of an unrecognizable man sitting alone on his bed and suffering from stomach cramps while home alone

We all get bloated once in a while, whether it's due to a big meal before bed or every woman's least favorite time of the month. But if you experience unexplained bloating on the regular, it could be a sign of colon, ovarian, stomach, and pancreatic cancers, according to Harvard Health.

Gastrointestinal issues

toilet against a sea green wall, diy hacks

Common digestive woes can also be a sign of colon cancer—and that's one of the reasons why it's such a life-threatening illness. "It's one of the deadliest illnesses out there because its symptoms are so mild that when they diagnose it, it's often too late," explains Nikola Djordjevic, MD, a practicing physician in Bor, Serbia. If you begin having issues with your bowel movements or notice blood in your stools, make an appointment with your doctor just to be safe.

Facial puffiness

bald man with blue eyes look at camera with swollen lower portion of face

Puffiness in the face is fairly common, especially if you've recently consumed more salty foods and alcohol than usual. But if the swelling in your face doesn't pass quickly or if it's more pronounced than usual, it could be a sign of a tumor, according to 2017 research published in The National Journal of Maxillofacial Surgery. Because tumors can restrict blood flow, they can cause blood to pool in the face and result in facial puffiness.

Caitlin Flynn
Caitlin Flynn is an award-winning writer and reporter who experienced early age corporate burnout in 2015 and traded New York City for the misty air and superior coffee of Seattle. Read more
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