Chronic cough etiquette?

I'm visiting Japan for the first time in the spring. I'm worried about how people will react to my dry cough. I've had it for over a year and it is due to hiatal hernia and gastric reflux. It is worse with talking, eating, and air changes. Should I wear a mask all the time? Should I have a note telling people that it is not an infection or will people not care that much?

I am glad to say that people around me here in Japan are back at caughing and sneezing without masks quite frequently again. People are still more conscious about it than before, but it is not like durign the pandemic when people in the entire room would turn their heads when someody would caugh.

I am afraid there is not much you can do. Many people won't mind anymore these days, while others may be worried. But there is just not much you can do about it.

Displaying an explanation seems awkward (although the thought of putting an explanation onto your mask would be kind of original/fun - in addition to being very awkward). Not sure whether wearing a mask will put people at ease, as it could be interpreted as a sign that you are actually sick.

I'd carry one all the time if you have a chronic issue.

Enclosed places like shops or trains might need to make a on-the-fly decision on wearing it.

If you get uncontrolled coughing fits all the time. Then just wear it all the time in enclosed spaces.

I think it would help if you try to find chances to tell people you're with that the cough is nothing infectious. Not only would the person with you be assured, but the people listening to your conversation would understand even if it's in plain English. As for etiquette, covering your mouth with a handkerchief or tissue is what people are supposed to do when coughing or sneezing even when it's not during a pandemic.

Otherwise, there's not much you could do. And whatever your policy is, carrying one mask around does help. You never know when and where you'd encounter ordinary people who prefer masks.

On a related note, it was a few years before the pandemic that someone I know was in a train sitting next to a person who kept coughing. The person I know kept sitting there because he didn't want to be rude. A few days later, he suffered a very severe cold with high fever, and promised himself never to keep sitting next to a coughing person. So you can't really blame someone for walking away.

I hope you have a great time in Japan!

according to my experiences, your throat get some damage every time when you get coughs and I think this damages have been accumulated.
what kind of treatments do you take to prevent coughs ?
wearing a mask gives your throat some moisture and it has an effect of reducing coughs, again from my experiences.

They said they are suffering from GERD. So I imagine they are receiving treatment or taking medication pre-emptively for that.

In answer to your question: just cough

There are people that have coughed all the time without masks. The real question you should be answering is if you're still dealing with a dry cough after a year and you think you have GERD, you need to figure out the issue and get rid of it and you won't have the coughing problem.

I actually had acid reflux/gerd before myself and got rid of it over time by taking apple cider vinegar in water. I encourage you to check out info yourself and see if it helps you and that way you won't have to worry about your cough any longer.

Good luck!