Hi. I know with computer, it is not recommended to use two different antivirus at the same time. Now, for android, is it safe to use both avast and lookout at the same time. Will there be any conflict?
No, there will be not. Off course you have to take care about SMS blocker. |IMHO lookout will prompt you in notification bar every time; turning off the lookout will bring more power life to your battery 
Using both Lookout and Avast! AT is redundant, as avast contains the same features and then some. There really is no point in keeping both
I would suggest you on having avast installed then lockout due to the avast does not need much processing power as unlike lockout
Great to see an official blessing and advice, thank you!
We had a related discussion on Thrives. One user uses Lookout with Avast, I use DrWeb (lists what apps I install which avast doesn’t). I see no effect on battery, but of course there has to be some even if tiny.
http://www.thriveforums.org/forum/toshiba-thrive-general-discussions/15294-anti-virus-2.html
also see pages 3 and 4 about what’s scanned and when, all the gory details.
Dusting off an old thread …
I keep getting nervous over this two-AV issue.
Yes, no problems under normal conditions.
BUT,
let’s say a trojan or something gets delivered from a website, and let’s say avast takes a shot at objecting and removing. Won’t the second AV (lookout, drWeb, whatever) at this point kick in and prevent avast’s cleanup? That’s what happens in windows when people run two AV.
Now in android it might be different, if so, can we get some reassurance that such a scheme is really safe and not reducing the protection at the time it’s most needed?
Well, this is good question; basically, android OS does not taking much care about apps, so they can race between - very usual problem on android devices. Avast! is trying to take the highest priority on application installation and/or run, so the engine will probably tell you about the malware first. Now when another antivirus will accessing the malware app and avast! will taking care of it, nothing will happen, because this is two threads accessing one object. In case the avast! will remove the malware app and the other antivirus is still scanning it or waiting with some kind of dialog the most probable result will be an error message, that application can not be removed, because it does not exist. Some problems could happen in case when the user has more than two antivirus apps installed - first, all of them will try to update, so time out error could pop up at one of them; at second, accessing via many threads one object could cause another exceptions and very slow response from the device. But generally said, having more than one AV application on the one device is not big problem.