Silent Killers: Terrifying Diseases You Could Have Without Knowing It

Conditions like high blood pressure and high cholesterol are scary, because it’s easy to have them and not know it. Unfortunately, this can happen with many damaging and even deadly diseases, too. People can live with certain types of cancer, autoimmune disorders, and a large number of STDs for years without even knowing they’re sick.

These are the most terrifying and dangerous diseases you might have right now, and not even know it.

1. Celiac disease

You could have celiac disease and not even know it.

Celiac disease often comes with no symptoms. |

Though gluten-free diets are growing more common among people without celiac disease, there are many people who do have it without knowing — and you could be one of them. According to the Celiac Disease Foundation, this is an autoimmune disease triggered by gluten, which is found in wheat, barley, and rye products. You may experience fatigue, joint pain, migraines, or depressive symptoms as you continue to eat gluten, but not always. No two cases of celiac are alike — and there are over 200 possible symptoms in adults. If left untreated, it can damage your small intestine.

Next: Are your bones in bad shape? Sometimes it takes a fracture to tell.

2. Osteoporosis

Osteoporosis isn't always painful, until you fracture a bone.

Bone loss as a result of aging can lead to osteoporosis. |

According to the National Osteoporosis Foundation, osteoporosis occurs due to bone density loss, but this doesn’t come with any signs or symptoms. The condition is responsible for over 2 million broken bones every year. Though some people lose height and posture as a result of osteoporosis, it sometimes takes years — or a bone fracture — to notice anything’s amiss. Older adults especially should make sure they’re getting enough vitamin D and calcium to prevent bone damage.

Next: Feeling thirsty? That could mean a lot of things.

3. Diabetes

High blood sugar is hard to detect without the proper tools.

You can have diabetes and not even know. |

Type 2 diabetes — the type you develop, not the one you’re born with — causes problems with blood sugar regulation, says the American Diabetes Association. Your body can’t use the hormone insulin properly, sending your blood sugar in a frenzy. Some of the most obvious diabetes symptoms involve feeling tired, thirsty, and experiencing an increased appetite. However, because exhaustion, thirst, and hunger aren’t all that uncommon in daily life, it’s difficult to rely on these symptoms to infer you have diabetes.

Next: Not all cancers have clear symptoms.

4. Colon cancer

Later stage colon cancer is harder to treat.

This type of cancer often has no signs or symptoms. |

Colon cancer is one of the sneakiest — and deadliest — cancers out there. Mayo Clinic says it begins as harmless, noncancerous polyps in your large intestine. Unfortunately, these can grow to become cancerous over time. Even though it’s a highly treatable form of cancer, people can end up living with it undetected for years if they skip their screenings. You may experience diarrhea, constipation, or blood in your stool as the condition progresses, but by this point, it’s grown beyond its early stages.

Next: You’ve probably never heard of this type of cancer before.

5. Liposarcoma

People can live with this type of cancer for months or even years.

Is it a fat cell deposit, or a tumor? |

Liposarcoma is a type of cancer that develops in fatty tissue, producing tumors you may not even notice. Unfortunately, these tumors look a lot like lipomas, which are collections of fat cells that grow just beneath the skin. Tumors in the arms and legs could grow for months or years undetected, which is especially dangerous if you have one of the more life-threatening types. Cancer Treatment Centers of America warns some more serious variations of liposarcoma can spread to your liver and lungs if it isn’t treated in time.

Next: Is breathlessness after climbing a flight of stairs really just a sign of aging?


COPD can make breathing difficult.

You may mistake your breathlessness as a harmless sign of aging. |

Chronic obstructive pulmonary disease (COPD) is a group of lung diseases difficult to detect early on. According to the COPD Foundation, coughing, tightness in the chest, and breathlessness usually develop before diagnosis. However, you could contribute these symptoms to a number of factors, like overworking or “just getting older.” Smoking is the greatest risk factor for developing COPD.

Next: Researchers still don’t know what causes this liver disease.

7. Fatty liver disease

Scientists don't know why fatty liver disease develops.

Obesity is just one NAFLD risk factor. | fac

Nonalcoholic fatty liver disease develops when fat builds up in your liver, causing inflammation and liver cell damage, says MedlinePlus. This type of fatty liver disease isn’t related to alcohol overuse. Both types, however, are “silent” — they develop without any symptoms — and researchers still don’t know the cause. You’re more likely to develop NAFLD if you have type 2 diabetes, high blood pressure, a metabolic disorder, or you are obese.

Next: An innocent stroll through the woods could result in disease.

8. Lyme disease

Lyme disease symptoms look like the flu.

Always check for ticks after spending time in the woods. |

Did you check yourself for ticks after your hike this afternoon? You should — especially if you want to avoid lyme disease. Even though it’s rare, according to Mayo Clinic, you can contract lyme disease from a single tick bite. Early on, lyme disease looks a lot like the flu — you might get chills, a fever, or feel tired. You’ve probably had the flu before, so you’re likely to assume fluids and rest will have you back in action in no time — instead of seeing a doctor for treatment.

Next: Are you sexually active? There are other risks besides pregnancy.

9. Chlamydia

This STD is treatable -- if you know you have it.

Chlamydia is one of the most common STDs in the U.S. |

Though it’s the most common STD in the United States, most people who have chlamydia are clueless. It doesn’t have symptoms — its infection can live in your vagina, cervix, urethra, rectum, or even your throat without warning. In post-menopausal women, its worst possible consequences are long-term pelvic pain, says the CDC, which is treatable. You should always get tested if you’re sexually active whether you suspect you have an STD or not.

Next: Chlamydia isn’t the only STD you have to worry about.

10. Gonorrhea

Like many STDs, gonorrhea doesn't always make its presence known.

Always get tested. Always. |

According to the CDC, gonorrhea is another STD that’s hard to detect in both genders. Both men and women may experience painful urination if they have this disease. However, that, along with vaginal bleeding in women or discharge from the penis in men, could be mistaken for a bladder infection. Most won’t get tested for an STD because of this, so it’s important to use protection and get tested regularly if you’re sexually active.

Next: If left untreated, this disease could lead to a heart attack.

11. Coronary artery disease

Heart disease causes chest pain, but people often don't take it seriously.

Heart disease can go unnoticed until it’s too late. |

Heart disease and many other heart conditions progress with terrifying stealth. Coronary artery disease, a type of heart disease, occurs when the arteries that supply blood to your heart become narrow and hard, limiting your heart’s blood supply. Chest pain or tightness are the most common symptoms. But according to Cleveland Clinic, acid reflux, pneumonia, back problems, and even panic attacks and stress can also cause chest pain — so you might simply dismiss it. If you experience chest pain that lasts longer than five minutes, it’s likely heart-related, and you should seek medical attention as soon as possible.

Next: You probably don’t notice this disease’s symptoms, which occur while you’re sleeping.

12. Sleep apnea

Sleep apnea can disrupt sleep.

It’s hard to notice symptoms when you consistently sleep through them. |

According to the National Heart, Lung, and Blood Institute, sleep apnea occurs when the muscles in your throat relax while you’re sleeping. This prompts your brain to wake you up to restore normal breathing — but you usually don’t notice. It’s hard to make note of symptoms that are prominent only when you’re asleep, which is why many people don’t know they have this problem. This disease is more common in people who drink or smoke, and in those who are overweight or obese.

Next: Sitting still for long periods of time is more life-threatening than you thought.

13. Deep vein thrombosis

Deep vein thrombosis doesn't cause symptoms in half the people who have it.

DVT can happen when you sit still for too long. |

When a blood clot develops in one of the veins of your lower leg or thigh, you may not even notice. If the clot comes loose, though, it could cause lung damage. You may experience tenderness, pain, redness or swelling in the affected area, but there’s a chance you won’t. The National Heart, Lung, and Blood Institute warns only half of people with DVT experience any of these symptoms. Avoid sitting for long periods of time to reduce your risk. Simply getting up and doing a few laps around the room is better than nothing.

Next: You probably didn’t know sexual contact could also spread this disease.

14. Hepatitis C

Hepatitis C can lead to liver damage in more severe cases.

A large percentage of people with hepatitis C are unaware. |

Hepatitis C is a liver-targeting virus that can be either mild or severe. The World Health Organization says injections and drug use can spread hepatitis C, but so can sexual contact. Some people develop a minor infection that heals itself over time. However, it can become chronic, which causes liver damage. About 80% of people don’t show any symptoms at all, so good hygiene and regular STD testing are your best bet in preventing long-term problems.

Next: You could go blind if this disease goes undetected.

15. Glaucoma

Many people with glaucoma don't know they have it.

Glaucoma symptoms are difficult to recognize. |

Despite presenting with few to no symptoms, glaucoma is the second leading cause of blindness in the United States. According to All About Vision, this and associated eye conditions causes optic nerve damage. Since your optic nerve can’t carry information to your brain, you can lose peripheral vision, or go totally blind. You may experience pressure behind your eyes, a subtle signal that something is wrong, but not everyone with this condition will feel it getting worse.