People with crystic fibrosis have thick and sticky mucus that traps bacteria. This causes lots of lung infections and often permanet lung damage. Mucus can interfere with how the pancreas works. This can make it hard for a child to absorb nutrients from food. You may notice that they have salty skin cystic fibrosis can cause a person to become easily dehydrated or to have very low salt levels. Also almost all men who have this are unable to father a child. Women who have it may have difficulty getting pregnant. People who have this may have weaker bones than other people. This is because their bones contain lower levels of minerals. Weakened bones can lead to fractures, osteopenia, or osteoporosis. Cystic fibrosis can also cause swollen or painful joints.