Chances are you know someone who has an invisible illness. An invisible illness means that a person is suffering from an illness or disease which isn't necessarily visible on the outside. However, just because you can't see what's wrong doesn't mean that there isn't anything wrong. People with invisible illnesses often need just as much practical and emotional support as those with illnesses you can see, but sometimes it can be difficult to know how to help. We've put together a list of things you should know about someone with an invisible illness based on information from prevention.com. Don't assume they're faking their disability. Just because someone has a disabled sticker in their car doesn't necessarily mean they're wheelchair-bound. Many people have these stickers because they need oxygen to get around or are waiting for organ transplants. Yes they might be able to walk, but they might not be able to walk very far and even a short distance can take a lot of effort. Four facts about fibromyalgia you might find interesting.