We know this is a pretty common rule of thumb that you hear-- and our answer is--maybe! Liquid makeup products are generally the quickest to expire, BUT common sense will be your best judge. With any makeup product you question, you can use your eyes and nose to detect whether the product is no longer good. If you can see a change in consistency, or if it smells different than it used to...it's time to toss it! Do NOT try to revive a thickened mascara by adding water or anything else to it. If you've had a mascara for over three months and it still seems like it's in good shape, you can give it a try. The only caveat is that liquid makeup products can harbor bacteria (which they pick up from the air and also contact with YOU), so you should not keep a mascara indefinitely even if it seems normal. Again, use your best judgement and toss it if there's any question!