TL;DR: As of today, no study found showing the effectiveness of Tegarome for any treatment. As of 12th Feb, I sent a message to the laboratory asking for a link to said study.
Looking up the product, I found one with the following statement:
In addition to that, the results obtained with this preparation have never been denied and have been the subject ...
The Buteyko Breathing Technique is one of several breathing exercises promoted to help asthma.
Cochrane publishes systematic reviews of health literature to inform health professionals about the evidence. They have done four such reviews of breathing exercises, two related to asthma:
Breathing exercises for children with asthma
Breathing exercises for ...
My answer is based on the article Buteyko Breathing Technique – Nothing to Hyperventilate About in Science-Based Medicine ("SBM"). The site claims:
SBM is a completely independent endeavor. We receive no industry funding and have no financial conflicts of interest. Our only goal is to promote high standards of science in medicine.
This article reviews ...