Is there a way to reduce the number of loops

Question

Good day everyone, my code is working well, but I want to reduce the number of loops. Below is my code, I'm trying to get all possible combinations of the arrays.

$arr = array(
        "a" => array("mild","moderate", "severe", "very_severe"),
        "b" => array("mild","moderate", "severe", "very_severe"),
        "c" => array("mild","moderate", "severe", "very_severe"),
        "d" => array("mild","moderate", "severe", "very_severe"),
        "e" => array("mild","moderate", "severe", "very_severe")
        );
$counter1 = $counter2 = $counter3 = $counter4 = $counter5 = 0;
for ($counter1=0; $counter1 < count($arr['a']); $counter1++) { 
    for ($counter2=0; $counter2 < count($arr['b']); $counter2++) { 
        for ($counter3=0; $counter3 < count($arr['c']); $counter3++) { 
            for ($counter4=0; $counter4 < count($arr['d']); $counter4++) { 
                for ($counter5=0; $counter5 < count($arr['e']); $counter5++) { 
                    echo $arr['a'][$counter1]. ", ". $arr['b'][$counter2]. ", ".$arr['c'][$counter3] .", ".$arr['d'][$counter4] .", ".$arr['e'][$counter5];
                    echo "<br/>";
                }
                
            }
        }
        
    }
}