Can I take two syrups at the same time - Phlegamine and marshmallow syrup - with a wet cough?

Yes, you can. There are no contraindications to the use of the drugs listed in the question at the same time. Phlegamine is an expectorant syrup that helps in relieving the symptoms of wet cough by thinning and facilitating the expectoration of secretions: https://www.gdziepolek.pl/produkty/30265/flegamina-classic-o-smaku-mietowym-bez-cukru-syrop/apteki Marshmallow syrup, on the other hand, is a plant product and has a protective effect on the respiratory tract, soothes throat irritation and contributes to the relief of cough: https://www.gdziepolek.pl/produkty/95434/syrop-prawoslazowy-amara-syrop/apteki I enclose additional information that may be helpful: https://www.gdziepolek.pl/artykuly/czy-przyjmowanie-kilku-lekow-jednoczesnie-jest-bezpieczne https://www.gdziepolek.pl/artykuly/kaszel-suchy-i-mokry-jak-go-leczyc