An old friend of mine who is living with HIV recently emailed me a story about a small study which looked at the safety of a 5 day on, 2 day off efavirenz based regimen.:
http://www.hivandhepatitis.com/2008icr/hiv9/docs/111808_a.html

He wanted to know what I thought. Here is what I wrote:
I know lots of people who do this and it is most likely pretty safe in most cases. A couple of caveats: First, the study in this article is very small, so its findings aren’t that reliable. Second there is a concern that people are more likely to have sex, including unprotected sex, on weekends- which would be much riskier off meds. Lastly, I tend to think that nothing is more toxic than untreated HIV. The meds can be a drag, but HIV causes damage to many types of cells and tissues- often through promoting inflammation. This kind of thing was not looked at in this study, and really couldn’t be. So, I tend to counsel against treatment interruptions, but totally understand if people choose to do them.

I used to be much more agnostic when it came to treatment interruptions. The SMART study and a bunch of work by immunologists evaluating how HIV effects the immune system independent of its impact on CD4 counts, led me to think that they are generally not a good idea.
I wish I felt differently. I do not like taking meds each day, even though I have no side effects from my current combo. While some studies, like the one he asked me about, have shown some degree of safety, the bulk of the evidence is that you are doing harm- quiet harm, but harm nonetheless.