5 weeks. We found that out at around 3w but couldn't get in to see the paed until 5w. I asked for the med. initially we didn't think it help but when I stopped giving him, his sudden scream and constant hiccup return immediately. He is still on it. Some days we stopped giving it to him because of traveling timing, he had the symptoms again. Dr wants us to wean him by 9 months but we will just play it by ears. He is nearly 7m now.