Yes, Advil, also known as ibuprofen, can decrease the effectiveness of antidepressants. According to a study, popular painkillers like Advil can impair the effectiveness of antidepressants [2]. The research found that people who took antidepressants and painkillers together were about twice as likely to not feel better as those who took antidepressants alone [2].

The study was conducted on people with depression who were taking selective serotonin reuptake inhibitors (SSRIs), a common type of antidepressant [3]. The study found that those who took SSRIs and anti-inflammatory drugs, such as ibuprofen, had a lower response rate than those who took SSRIs alone [3].

It's important to note that the study does not prove that painkillers cause antidepressants to be less effective, only that there is a correlation between the two [1]. However, the study suggests that people should be cautious when taking painkillers and antidepressants together [2].

In conclusion, based on the available information, it can be said that Advil can decrease the effectiveness of antidepressants. It is advisable for individuals to consult with their healthcare provider before taking any medication, especially if they are currently on antidepressants.

Sources:
[1] <https://www.drugpatentwatch.com/p/tradename/ADVIL>
[2] <https://www.npr.org/sections/health-shots/2011/04/25/135715226/popular-painkillers-can-impair-antidepressants-effectiveness>
[3] <https://www.nbcnews.com/health/health-news/painkillers-can-reduce-antidepressants-effect-flna1c9461639>