As mentioned in a sibling, try looking at Mucinex a try. There is a 12h version that has Guaifenesin https://en.wikipedia.org/wiki/Guaifenesin and Dextromethorphan https://en.wikipedia.org/wiki/Dextromethorphan as the only two active ingredients.

Compare with Dayquil - Acetaminophen 650 mg (pain reliever/fever reducer), Dextromethorphan HBr 20 mg (cough suppressant) and Phenylephrine HCI 10 mg (nasal decongestant).

> Guaifenesin, also known as glyceryl guaiacolate, is an expectorant medication taken by mouth and marketed as an aid to eliminate sputum from the respiratory tract.

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> Guaifenesin is used to try to help with coughing up thick mucus, and is sometimes combined with the antitussive (cough suppressant) dextromethorphan, such as in Mucinex DM or Robitussin DM.

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> Dextromethorphan (DXM), sold under the trade name Robitussin among others, is a cough suppressant used in many cough and cold medicines.

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> The primary use of dextromethorphan is as a cough suppressant, for the temporary relief of cough caused by minor throat and bronchial irritation (such as commonly accompanies the flu and common cold), or from inhaled particle irritants, as well as chronic cough at a higher dosage.

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The combination of the two is designed to reduce coughing and when you do cough, it is much more productive with the expectorant and cough suppression. It isn't a decongestant, but it has (personal anecdotal take) a good effect on getting rid of the secondary effects of congestion.