Q: Can people who are allergic to shrimp and crab eat chitin? A: Chitin is a “chitosan” made from the shell of shrimps and crabs. It is a type of ingredient that could easily cause allergic reactions. Thus, this can cause those who have an allergic body constitution, to suffer allergic reaction which will be manifested as skin itch or pimples on their skin. In severe cases, it can also cause symptoms such as asthma and body convulsion. So it is highly not recommended for people who are allergic to shrimps and crabs to consume chitin.