A study published in the Singapore Medical Journal looked at the effectiveness of Danzen (serrapeptase) on breast engorgement in 70 patients.

Danzen was given to the patients over a period of three days, and an independent observer monitored and assessed the signs of engorgement unaware of whether the patients was receiving the serrapeptase or the placebo.  The results showed a significant improvement in patients receiving the Danzen treatment when compared to the group receiving the placebo.

The groups concluded that Danzen was a safe and effective treatment of breast engorgement.

Reference:

The treatment of breast engorgement with Serrapeptase (Danzen): a randomised double-blind controlled trial.