Not if you break the seal properly. A first-time user may have some discomfort the first few times, but it will lessen with practice. Squeeze the cup gently, to let some air in and break the seal. Inserting a finger alongside the cup also helps this process. Sometimes there are certain medical conditions (such as vaginismus) that can cause pain with any kind of insertion, even small objects. There are other conditions that can cause this too. If you suspect that you may have such a condition, please see your doctor for a proper diagnosis.