Several approaches can help thin and clear excess mucus, from simple home remedies like steam and saline rinses to over-the-counter expectorants. What works best depends on where the mucus is (chest vs. sinuses) and whether you’re dealing with a short-term cold or a chronic issue. Here’s what actually has evidence behind it.
Saline Nasal Rinses for Sinus Mucus
If the mucus is mostly in your nose and sinuses, a saline rinse is one of the most effective things you can do. Using a neti pot, squeeze bottle, or bulb syringe to flush saltwater through your nasal passages physically washes out thick mucus and irritants. A meta-analysis comparing different concentrations found that slightly saltier-than-body solutions (hypertonic saline) provided greater symptom reduction than standard isotonic saline, though both helped.
The one safety rule you cannot skip: never use plain tap water. Tap water can contain amoebas that, if they reach the brain through the nasal passages, cause nearly always fatal infections. The CDC recommends using store-bought distilled or sterilized water, or tap water that has been boiled at a rolling boil for one minute and then cooled. At elevations above 6,500 feet, boil for three minutes. Pre-mixed saline packets from a pharmacy make this easy.
Over-the-Counter Expectorants
Guaifenesin, the active ingredient in products like Mucinex and Robitussin, is the only OTC expectorant available in the U.S. It works by thinning the mucus in your airways so it’s easier to cough up. It won’t suppress your cough or dry you out. Instead, it makes coughing more productive, which is the goal when thick mucus is sitting in your chest.
For children, the rules are stricter. The FDA warns that children under two should never receive any OTC cough and cold product containing a decongestant or antihistamine, as reported side effects have included seizures, rapid heart rates, and death. Manufacturers voluntarily relabeled these products to say “do not use in children under 4 years of age.” For kids four and older, follow the dosing on the pediatric label carefully, and never give a child adult-formulated products.
Honey for Cough and Mucus
Honey is surprisingly effective for mucus-related coughing, particularly in children over one year old. In a Cochrane review of randomized controlled trials involving 265 children, honey performed better than no treatment, slightly better than diphenhydramine (an antihistamine), and about equally to dextromethorphan (the most common OTC cough suppressant). A separate study of 134 children found that over 80% of those given honey with milk saw their cough decrease by more than half, a rate statistically similar to OTC medications.
Notably, those same OTC cough suppressants were found to be no better than placebo at relieving nighttime cough symptoms in children. So honey isn’t just a folksy alternative; it performs as well or better than most of what’s on the pharmacy shelf for kids. A small spoonful before bed is a reasonable dose. Never give honey to infants under one year due to the risk of botulism.
Humidity and Steam
Dry air thickens mucus and irritates already-inflamed airways. Adding moisture to your environment helps keep mucus loose enough to move. A warm shower, a bowl of steaming water with a towel over your head, or a humidifier in your bedroom can all provide relief.
If you use a humidifier, keep your indoor humidity between 30% and 50%. Going above 50% creates a breeding ground for mold, dust mites, and bacteria, which can make congestion worse and trigger allergy or asthma flare-ups. Clean the humidifier regularly to prevent the same problems inside the device itself.
Hydration: What the Evidence Actually Shows
You’ve probably heard that drinking lots of fluids helps thin mucus. The logic makes sense: mucus is mostly water, so more fluids should make it less sticky. But a Cochrane review found zero randomized controlled trials that actually tested whether increasing fluid intake improves outcomes in acute respiratory infections. The recommendation is based entirely on reasoning, not direct evidence.
That said, staying adequately hydrated still matters. Fever and rapid breathing increase fluid losses, and dehydration genuinely can make mucus thicker. The practical takeaway is that you should drink enough to stay hydrated (water, broth, tea, whatever you prefer) but there’s no proven benefit to forcing fluids beyond your normal needs.
NAC: A Supplement Worth Knowing About
N-acetylcysteine (commonly called NAC) is a supplement that breaks the chemical bonds in mucus, making it thinner and easier to clear. It’s widely used in Europe as a mucolytic and is available over the counter in the U.S. as a dietary supplement. The evidence is strongest for people with chronic respiratory conditions. In patients with COPD, a large trial called PANTHEON found that 1,200 mg daily for 12 months reduced the frequency of flare-ups, especially in moderate disease. A separate study in patients with bronchiectasis found similar benefits at the same dose over 12 months.
For short-term mucus from a cold or flu, NAC has less robust evidence, but the mucolytic mechanism is the same. The standard dose in most studies is 600 mg once or twice daily. It has a strong safety profile even at higher doses, with side effects generally comparable to placebo in controlled trials.
What Mucus Color Does (and Doesn’t) Tell You
Green or yellow mucus is widely believed to signal a bacterial infection that needs antibiotics. This is mostly a myth. The green color comes from an enzyme released by white blood cells as part of the normal immune response, which happens whether the infection is viral or bacterial. A study in the Scandinavian Journal of Primary Health Care confirmed that sputum color cannot reliably distinguish between viral and bacterial infections in otherwise healthy adults. Clear, white, yellow, green, and even blood-tinged mucus can all appear during a simple viral cold.
Mucus color alone is not a reason to seek antibiotics. What matters more is how long symptoms last (worsening after 10 days or improving then worsening again), the presence of high fever, or severe facial pain, which can point toward a bacterial sinus infection that may benefit from treatment.
Does Dairy Make Mucus Worse?
Many people swear that milk and cheese make their mucus thicker or more plentiful. There’s limited but real evidence behind this for people who already have mucus problems. In a blinded, randomized trial of 108 adults who reported excessive nasal mucus, those assigned to a dairy-free diet for six days saw a significant reduction in self-reported mucus levels. When dairy was reintroduced on day four in the dairy group, mucus scores climbed back up significantly.
This doesn’t mean dairy causes mucus production in everyone. But if you’re already congested and notice dairy seems to make it worse, cutting it out temporarily is a low-risk experiment. For most healthy people without active congestion, dairy has no meaningful effect on mucus.