What is a hidden, chronic illness?

A hidden, chronic illness is a longtime/recurring condition or disease whose symptoms aren’t apparent to the outside world. Individuals with hidden, chronic illness aren’t visually identifiable.

There is a variety of terminology associated with hidden, chronic illness. InvisAbilities uses “hidden, chronic illness”, “invisible illness”, “invisible disability” and “invisAbility” interchangeably.

Below are some examples of invisible illnesses. Since the realm of invisible illness is so large, this is a non exhaustive list. The purpose of this list is to provide a brief overview of the debilitating symptoms that accompany many hidden, chronic illnesses.


Addison’s Disease

A condition where the adrenal glands don’t produce enough hormones. 
Changes in blood pressure or heart rate, chronic diarrhea, fatigue, salt craving, weakness. 


Closely related inherited disorders that disrupt the metabolism of very long chain fatty acids.
Changes in muscle tone, hearing loss, hyperactivity, seizures.

Allergic Reactions

An immune system reaction that occurs soon after ingesting a specific food/drug or receiving an insect bite.
Abdominal pain/cramping, anxiety, diarrhea, difficulty breathing, light-headedness, itchiness.


A life-threatening allergic reaction.
Abdominal pain/cramping, anxiety, diarrhea, difficulty breathing, light-headedness, itchiness.

Ankylosing Spondylitis

A long term disease that causes inflammation of the joints and spinal bones.
Loss of appetite, pain, stiffness, weight loss.

Acquired Immune Deficiency Syndrome (AIDS)

Final stage of HIV disease that attacks the immune system.
Chill, fever, swollen lymph glands, weakness, weight loss.


A condition where the arachnoid lining around the nerves becomes inflamed.
Bladder dysfunction, stinging pain, tingling.

Autoimmune Hepatitis

An illness where the body’s immune cells attack the liver and cause inflammation.
Abdominal distension, dark urine, fatigue, itchiness.


Inflammation of the bursa (fluid filled sack between tendons and skin or tendons and bone).
Joint pain and tenderness, stiffness and swelling.


A disease where there is uncontrolled growth of abnormal cells in the body (e.g. Breast, thyroid, prostate).
Pain, chills, fatigue, fever, weight loss.

Celiac Disease

A reaction from eating gluten damages the small intestine and prevents proper absorption of nutrients.
Abdominal pain, constipation, diarrhea, nausea, vomiting.


A form of inflammatory bowel disease, causing inflammation of the large intestine.
Abdominal bloating, bloody stool, chills, dehydration, diarrhea.

Crohn’s Disease

A form of inflammatory bowel disease, causing inflammation of the lining of the digestive tract.
Abdominal pain, constipation, fatigue, rectal bleeding, liver inflammation, weight loss.

Chronic Fatigue Syndrome

A disorder characterized by extreme fatigue that can’t be explained by any underlying medical condition; fatigue does not improve with rest.
Fatigue, memory loss, sore throat, headache, muscle ache.

Chronic Kidney Disease

Gradual loss of kidney function.
General ill feeling, general itching, fatigue, headache, nausea.

Chronic obstructive pulmonary disease (COPD)

Breathing difficulties due to either chronic bronchitis, or emphysema.
Cough, fatigue, respiratory illness, shortness of breath.
Chronic Prostatitis (or Chronic Pelvic Pain)

Swelling and inflammation of the prostate gland, a walnut-sized gland located directly below the bladder in men 
Painful orgasms, frequent, urgent and painful urination, pain in the abdomen, groin or lower back and the area between the scrotum and the rectum, discomfort of the penis or testicles 

Chronic Thyroiditis

Inflammation and swelling of the thyroid gland that reduces thyroid function.
Difficulty concentrating, dry skin, fatigue, enlarged neck.

Cystic Fibrosis

Genetic illness with build up of thick mucus in body especially in the lungs and digestive tract.
Belly pain from severe constipation, difficulty breathing, fatigue, nasal congestion, weight loss.
Dercum’s Disease
A condition characterized by multiple, painful liopmas (lumps).
Chronic pain in the adipose tissues, fatigue, weakness, joint and muscle aches, rapid heartbeat, sleep disturbances, diabetes.

A mood disorder that causes a persistent feeling of sadness, hopelessness and  and worthlessness; triggers vary but may include biological/genetic factors, hormones, life events etc. 
Fatigue, aches and pains, weight gain/loss, increase decrease in sleep, anxiety, decreased sexual desire, difficulty focusing.


A chronic disease where there are high levels of sugar in the blood.
Blurry vision, excessive thirst, fatigue, frequent urination.


A painful disorder in which tissue that normally lines the inside of the uterus (the endometrium) grows outside the uterus. 
Painful periods, pelvic pain, excessive bleeding, pain with urination, bowel movements and intercourse, infertility.

Ehlers-Danlos Syndrome

A group of disorders characterized by loose joints and hyper-elastic skin.
Early arthritis, joint dislocation, poor wound healing.


A disorder that results from surges in electrical signals inside the brain.
Temporary confusion, staring spell, uncontrollable jerking movements, loss of consciousness.


A chronic syndrome of body-wide pain and tenderness.
Concentration problems, migraine headaches, pain.


A kidney disease that damages the areas that filter waste from the blood.
Bloody or foamy urine, fever, joint aches.

Interstitial cystitis

Chronic inflammation of the bladder wall.
Pain during intercourse, urinary discomfort, urinary frequency and urinary urgency.

Human immunodeficiency virus infection (HIV)

A condition that gradually destroys the immune system.
Fatigue, fever, headache, muscle stiffness, sore throat, swollen lymph glands.


An endocrine disorder where too much parathyroid hormone is produced.
Back pain, blurred vision, fatigue, nausea.


An endocrine disorder where not enough parathyroid hormone is produced.
Abdominal pain, cataracts, seizures, tingling.


A condition where the thyroid overproduces thyroid hormone.
Difficulty concentrating, increase appetite, increased sweating, restlessness.


A condition where the thyroid under produces thyroid hormone.
Depression, fatigue, pain, sensitivity to cold, weakness.

Irritable Bowel Syndrome (IBS)

A disorder that affects the large intestine (colon), but does not cause permanent damage.
Abdominal pain and cramping, bloating, gas, diarrhea or constipation, mucus in stool.


An autoimmune disease that may affect skin, joints, kidneys, brain, and other organs due to the immune system attacking healthy tissue, causing inflammation.
Fatigue, fever, joint pain, mouth sores, sensitivity to sun, swollen lymph nodes, memory loss, malar rash.

McArdle syndrome

The inability to breakdown glycogen.
Burgundy-coloured urine, fatigue, muscle cramps, pain, stiffness, and weakness.


A severe form of headache, typically causing intense throbbing or pulsing in a concentrated area.
Nausea, vomiting, numbness, blurry or splotchy vision, sensitivity to light and sound.

Multiple Chemical Sensitivity

A condition attributed to exposure to low levels of chemicals (e.g. smoke, pesticides, plastics, synthetic fabrics, scented products, petroleum products and paints).
Headache, migraine, poor memory, sore throat, vomiting, fatigue, sensitivity to light and sound.

Multiple Sclerosis (MS)

An autoimmune disease that causes demyelination in the brain and spinal cord.
Decreased attention span, dizziness, double vision, fatigue, numbness, tingling.


Bone marrow disorder where marrow is replaced with scar tissue.
Bone pain, fever, easy bruising and bleeding, fatigue, enlarged spleen and liver, night sweats.


A chronic sleep disorder characterized by overwhelming daytime drowsiness and sudden attacks of sleep.
Falling asleep without warning (anywhere, anytime), loss of muscle tone, sleep paralysis, hallucinations.

Obstructive Sleep Apnea

A condition where pauses in breathing occur during sleep.
Forgetfulness, irritability, excessive daytime sleepiness.

Optic Neuritis

Inflammation of the optic nerve.
Loss of vision, pain with eye movement.


A skeletal muscle inflammatory disease.
Difficulty swallowing, muscle pain and weakness, shortness of breath.

Pulmonary Hypertension

Abnormally high blood pressure in the arteries of the lungs.
Chest pain, dizziness, fainting spells, fatigue, weakness.

Rheumatoid Arthritis

An autoimmune disease causing inflammation in the joints.
Fatigue, loss of range of motion, pain, stiffness.


An autoimmune disease that attacks healthy body tissues such as skin, blood vessels, muscles, and internal organs.
Constipation, joint pain, hardening of skin.

Sickle Cell Anemia

A disease in which red blood cells are abnormally crescent shaped.
Bone pain, breathlessness, fever, rapid heart rate.