Is it possible to use acetylcysteine, carbocysteine and erdosteine together?

The combination of the above substances is, in my opinion, unjustified and may even be harmful to health. All the compounds mentioned by you belong to the same pharmacological class - to mucolytics (according to ATC - group R05CB). So they have a similar mechanism of action, indications and expected effects after application. These drugs cause liquefaction and a decrease in the viscosity of secretions in the respiratory tract. In my opinion, it will be sufficient to use one of these compounds in the appropriate dosage and form. Combining several analogous products may not give a better effect, but only increase the risk of side effects. Depending on the exact nature of the health problem, other drugs that support the condition of the respiratory tract and reduce the density of mucus - for example, topical preparations or products of natural origin - can be added and increase the hydration of the body. I enclose information that may be of interest to you: https://www.gdziepolek.pl/kategorie/kaszel-mokry https://www.gdziepolek.pl/artykuly/kaszel-suchy-i-mokry-jak-go-leczyc https://www.gdziepolek.pl/substancje/carbocisteine https://www.gdziepolek.pl/substancje/acetylocysteina https://www.gdziepolek.pl/substancje/acetylocysteinaerdo