Is is possible to test positive for hiv and then test negative later?

It is possible, but EXTREMELY unlikely. This is assuming that the "positive" test you received was confirmed. For eg. when a person is tested for HIV, the first test is an ELISA antibody test which will pick up those infected, as well as those who may be infected. That is why a confirmatory test (A Western Blot antibody test) is required for a diagnosis of HIV to be given.

It is very very very very rare for a false positive to happen when both ELISA and WB are included (which is why it is diagnostically required that they both be done BEFORE a diagnosis is given.).

So, yes it is possible, just HIGHLY unlikely. I have never seen one personally, nor have any of my colleagues. It is so unlikely!!!!!!!!

If people are only given an ELISA antibody test that comes back "REACTIVE" (they don't use the words positive) and then a Western Blot which is non-reactive......they did not test positive for HIV with just the ELISA as the WB is required for a diagnosis....they may feel they had a false positive HIV test, but really it was a false reactive to one of the tests necessary to diagnose HIV infection

Another possible scenario that would be possible with your description:
When an HIV+ person's immune system is so damaged and practically not functioning, it is possible for them to serorevert and actually test HIV -. It doesn't mean they are HIV-, just that they can't produce the antibodies anymore. At this point, death would be, most-likely imminent.

If you are on medication for HIV (anti-viral medication) the test can come out negative. This may be because your viral load is low, but does not mean you are cured of the virus and it you can still transmit it.

Its possbile, but it never happens. You have better chance of winning a 1 million dollar lotto, then getting a false postive now a days. These tests are super senstive and very very very very very i can stress enough give a false postives.

Yes, it can happen, and is very devastating when it does.

yes it is, this is called a false positive.

yes.. but your already high risk of getting it again