Invisible illnesses are conditions patients have that are not obvious when looking at them. Often people with an invisible illness face a lot of prejudice; others accuse them of faking, lying or exaggerating their illness. People just don't fully understand what patients with invisible illnesses are going through. Just because you cannot see a person's illness doesn't mean they don't have one. Just because a person looks OK doesn't mean that they're feeling OK. Invisible illnesses often have no cure and patients need to take medication for the rest of their lives to help control and manage the symptoms. Here are some of the invisible illnesses that could be affecting your friends and colleagues that you wouldn't know about unless they told you (based on information from bustle.com): Cancer comes in many different forms and certainly for most cases you wouldn't know a person was being treated for cancer unless they told you. While chemotherapy can often make cancer patients lose their hair, other forms of cancer treatment leave no visible outward signs. Discover some yoga poses to relieve symptoms of Crohn's disease. Scleroderma is an autoimmune disease that causes an over-production of collagen. This can lead to problems with skin thickening, joint pain, and internal organ complications. While many scleroderma patients suffer from obvious facial and body changes, other scleroderma patients will not have any visible signs of the disease or signs that are hard for an untrained eye to spot. Read about six inflammatory bowel disease treatments options here. Cystic fibrosis is a disease where patients have an increased level of mucus in their vital organs. This primarily affects the lungs and pancreas and is life-threatening.