extending entry permit for medical reasons

What kind of visa have you ?

It's not difficult, just costs 1900 Bt at the Immigration on Suan Plu Road, off Sathorn Road. If you came in on 30 day entry stamp you can get 10 more days and no more! (Or is it only 7 days?). If you came in on two month visa, you can get 30 day extension. Since you are not sure about how long you need to stay, better to run to the border and just get a new 30 day entry stamp. You can see many of these border run bus services in the Bangkok Post.

Thai Immigration Bureau can be useful and will list your local Immigration bureau as you do not mention where you are. They are normally very helpful and sympathetic when medical reasons cause an extension request. A letter from your Doctor of Hospital is, of course, required.

You don't mention if your visa has been extended already if not a tourist visa can be extended and a 30 days visa free permission can be extended. Both cost B1900 and you must apply at an Immigration bureau.

If there is anything else that's a problem then call them on 022 873 101 and they speak good English and are veery helpful.

Hop you get better soon!

There is a special exemption for medical purposes from having overstay etc without having to do a border/visa run - obviously if you are getting it for medical purposes you can not travel even to the border.

The OP will get his 10 days or so without having to prove anything but for longer periods medical cert's etc are required.

I ka guy we had extended quite a bit - a couple of months till he shuffled over till the next life.

where are you; what kind of visa do you have; has it already been extended or not

but regardless, if you've a genuine medical reason (especially if you're not fit to travel) it won't be a problem - either visit any immigration bureau office in person, or else contact them for details of how to apply without going in person (the latter is only possible if you're incapacitated)

I have a typical tourist visa--30 days which they gave me at the airport. I've been having root canals done and there's been too much inflammation do it within 30 days. It might only be an extra week, or maybe two, that I need to stay. I can get around, though I have to take lots of antibiotics.
If I do a border run, where would be a good place to go? Is it possible to see Angor Wat and get this extension? (I have no idea how long it takes to get there--I'm in Bangkok, by the way.)
I'm sure my doctor would write me a note.
Is it the same price--B1900--if I do a border run?
Thanks everyone. Your help is very much appreciated.

What you have is not technically a Visa to the Thai Immigration. They call it a permission to stay for 30 days for tourism purposes Visa Free. You can go to Immigration and have it extended for 10 days - 15 if you are lucky, or have a Doctors note this costs B1900. Alternatively you can exit Thailand and re-enter when they will give you, for free, another 30 days, also extendable.

Sea

If you do a border run to Cambodia at Poipet the 30 days back into Thailand wil be free - the Cambodian visa will be 1000THB howevr with maybe 1 or 2 hundred more if they can sting you.

The bus from Mor Chit takes 4.5 - 5 hours and can be done in a day but leave from Morchit early as possible to try and beat the rush at lunchtime when the KSR and other crowds get there.

Recently there have been reports of massive queues at the border with waits of up to 3 hours in the blazing sun.

You could go on to Siem Reap for Angkor from here and it is well worth it.

Alternatively you could travel later from BKK and stay overnight in Aranypathet then head to the border very early and then back to BKK

Or get a flight to Siem Reap with Bangkok Air. I just checked and got quoted 10,000B, but you might get bcheaper if you try some different dates.