The OTC ones are mainly herbal so shouldn't be a problem but I really don't know.
I would strongly recommend you see your GP if you believe that you have a water retention problem. A big side effect of any diuretic is the frequent need to pee and water retention can be a serious problem.
The first and only time it's happened was when I was in Malta last year. My legs went massive. Went to a pharmacist who sent me to a doctor. The doctor gave me tablets and told me to take them a few hours before I tend to go out because of the peeing issue. They didn't make me pee any more than normal even though they worked for the swelling really well.
If I can get some over the counter here it'll save me time and money seeing a doctor if I need them when I get there.
Mid May for the Ginger ones B'day. I don't ever get water retention but this was a joke. My ankles were the same size as my knees and I looked like a complete pleb.
Must say they were brilliant in Malta. Pop into chemist and have an appointment with a doctor within 10 minutes. He gave me a proper check up....blood pressure, heart rate, chest, lifestyle questions....It's worth the 25 Euros but I'd rather prevent it :-)
some of them make you pee like Niagara, but other ones work just as well while being more gentle; but I don't know about over-the-counter ones. Did they have any idea why this suddenly happened? It's not like there's anything special about the Maltese air.
It'll be worth taking some Aquaban or similar, then, ummmm. If they don't work well for you should you get the same problem again you can always go back to the pharmacist.