Intravenous L-Citrulline for Vaso-occlusive Pain Episode in Sickle Cell Disease

The goal of this clinical trial is to learn if intravenous citrulline works to treat acute pain in hospitalized patients with sickle cell disease. It will also learn about the safety of intravenous citrulline. The main questions it aims to answer are: * Does intravenous citrulline decrease the duration of sickle cell pain during hospitalization * What medical problems do participants have when taking intravenous citrulline? Researchers will compare intravenous citrulline to a placebo (a look-alike substance that contains no drug) to see if intravenous citrulline works to treat acute pain. Participants will: * Receive baseline tests and intravenous citrulline for 16 hours during the hospital stay * After hospital discharge, visit the clinic in about 30 days for checkup and tests