My mum reported a reaction to MSG while on a China tour in 2011:

“We'd been in Shanghai for three days, eating three Chinese meals a day. I started to feel sick and developed a headache on the fourth morning. Had a coffee and cake thinking it might help. Then we had lunch, another Chinese meal. After lunch we were catching a bus to a market and then on to an overnight train trip to Sian. While waiting for the bus I started to feel faint. I sat on a step. I must have said at this stage that I thought it was a reaction to MSG, because I'd had headaches and nausea from it before. My sister encouraged me to get up when the bus came but I got as far as the gutter and collapsed into anaphylaxis. I was barely conscious, couldn't move. Our tour leader called an ambulance and one came fairly promptly, I think. In the ambulance a herb-y tablet was put under my tongue. Apparently my blood pressure was very low. My sister was with me, very concerned.

At the hospital I was taken to a private room and put on, first, a vitamin C drip then a ginkgo biloba one, over several hours. I revived enough to ask what they were giving me. Meanwhile, our tour leader was phoning ahead to ask for no MSG in any of our meals. Several of the group had been feeling off. While no-one in China would talk openly about MSG, the absence of it from the rest of our meals certainly made a lot of people feel better. My doctor, when we returned, agreed that MSG was most likely the cause of my collapse.” - Australian dietitian