A pharmaceutical composition has a stuffy nose deblocking activity. The composition includes a hyperosmolar aqueous solution of a non-ionic osmolality adjusting agent, optionally in combination with an ionic osmolality adjusting agent, wherein the composition further includes iota-carrageenan and/or kappa-carrageenan as an active antiviral ingredient in an antivirally effective amount, with the proviso that the composition in its ready-for-use formulation contains no more than 0-1.5% w/v of the ionic osmolality adjusting agent. The composition is useful for deblocking a stuffy nose and for prophylactic or therapeutic intervention of a number of viral infections of the upper respiratory tract.