With a doctor's approval, adults can take a decongestant. “If it's a short flight, take it [the decongestant] before leaving,” House says. If it's a long flight, eight hours or so, you might take it an hour or so before the scheduled landing.

It is generally considered safe and even beneficial to take Mucinex (guaifenesin) before a flight if you are dealing with chest or sinus congestion. Mucinex works by thinning the mucus, making it easier to clear from your system. During a flight, the low humidity and pressure changes can cause mucus to thicken and trap air in your sinuses or ears, leading to "airplane ear" or painful sinus pressure. By thinning the mucus, Mucinex helps your Eustachian tubes stay clear, allowing your ears to equalize more easily during takeoff and landing. However, you should be cautious if taking "Mucinex-D" or "Mucinex Fast-Max," as these contain decongestants or stimulants (like pseudoephedrine) that can cause jitters, increased heart rate, or dehydration, which is already a concern in a dry cabin. In 2026, doctors recommend starting the medication a day before your flight and staying exceptionally hydrated. As with any medication, always consult with your physician before use, especially if you have high blood pressure or are taking other prescriptions.