What Is Mar-Cof CG? Uses, Dosage, and What You Need to Know in 2026

Mar-Cof CG is a prescription combination cough syrup that contains two active ingredients — codeine phosphate and guaifenesin. It is used to temporarily relieve cough and chest congestion caused by the common cold, flu, or allergies.

If you've been prescribed Mar-Cof CG and want to understand what it does, how to take it correctly, and what to watch out for, this guide covers everything you need to know.

What Is Mar-Cof CG?

Mar-Cof CG is the brand name for a combination of:

• Codeine Phosphate 7.5 mg per teaspoon (5 mL): An opioid antitussive (cough suppressant) that works by suppressing the cough reflex in the brain
• Guaifenesin 225 mg per teaspoon (5 mL): An expectorant that thins and loosens mucus in the airways, making it easier to cough up

It is manufactured by Marnel Pharmaceuticals, LLC and is available as an alcohol-free, sugar-free liquid in 16 fl oz (473 mL) bottles. It is classified as a DEA Schedule V controlled substance because of the codeine content, which means you need a valid prescription to obtain it.

What Is Mar-Cof CG Used For?

Mar-Cof CG is indicated for the temporary relief of:

• Cough caused by the common cold, flu, or upper respiratory tract infections
• Chest congestion associated with bronchial irritation
• Cough with excessive mucus (productive cough) that needs both suppression and expectorant activity

Mar-Cof CG should NOT be used for cough caused by smoking, asthma, or emphysema. It is for short-term use only — up to 7 days. If your cough doesn't improve within 7 days, you should contact your doctor.

Mar-Cof CG Dosage: How to Take It

Always follow your doctor's or pharmacist's instructions. General dosage guidance from the labeling:

• Typical adult dose: 1 teaspoon (5 mL) every 4 hours as needed. Do not take more than 6 doses in 24 hours.
• Use an accurate measuring device: Do not use a household spoon — use the dosing syringe or measuring cup provided, or ask your pharmacist for a measuring device.
• Not for children under 18: The FDA recommends against use in patients under 18 due to risk of respiratory depression.
• Short-term only: Use for no more than 7 days unless your doctor has directed otherwise.

Who Should NOT Take Mar-Cof CG?

Mar-Cof CG is not appropriate for everyone. Do not use it if:

• You are allergic to codeine, guaifenesin, or any ingredient in the product
• You have asthma, COPD, or any condition causing breathing difficulty or respiratory depression
• You are under 18 years old
• You are pregnant or breastfeeding (discuss with your doctor — significant risks exist)
• You have taken an MAOI antidepressant within the past 14 days

How to Store Mar-Cof CG

Store at controlled room temperature (59°–86°F / 15°–30°C). Do not freeze. Keep out of reach of children. Because it contains codeine, store it in a secure location and keep track of the amount used. Codeine is a drug of abuse — if you notice the amount decreasing unexpectedly, contact your doctor.

How Mar-Cof CG Compares to Other Cough Medicines

Mar-Cof CG is one of several codeine-guaifenesin combination products available. Other brand names for the same or similar combination include Guaiatussin AC, Cheratussin AC (now discontinued), and Robitussin AC. These are all therapeutically similar to the generic codeine/guaifenesin oral solution. If Mar-Cof CG is unavailable at your pharmacy, see our alternatives guide for a comparison of substitute options.

If you need help finding Mar-Cof CG at a pharmacy near you, medfinder.com can help — we call pharmacies on your behalf and text you the results.