The FAA published a decision-making guide about OTCs on April 28, 2021.

You can download the advisory here:

• An OTC medicine is not safe simply because you don’t need a prescription.
• OTC medications commonly cause aeromedical side effects like sedation.
• Any medical problem, regardless of how or if it is treated, requires the pilot to consider 61.53 Prohibition on Operations During Medical Deficiency