These natural herb products may not be FDA approved however these gentle herbs have been used extensively in European and North American holistic medicine.Mullein has been used traditionally as a remedy for the respiratory tract, including bronchitis for years.
Ref: https://www.healthline.com/nutrition/mullein-tea#bottom-line

We are a UK-US based company and as of now this product is not yet available to local markets or health store but we are planning to get into it. As of now, we can ship and deliver our Mullein products to your location.

Some of our clients feel the effect within a week of consuming mullein but some take a little longer. Since every person has different adaptability we cannot predict how soon you will feel the effects but rest assured that with continuous usage you will eventually feel its result.

Mullein has been used traditionally for people with asthma, COPD, emphysema, bronchitis, inflammation, respiratory allergies, recurring congestion, smoker's cough, exercise-induced lung strain, and anxiety-related breathing issues.

Ref: https://www.webmd.com/diet/health-benefits-mullein-tea#1

Mullein is considered to be an extremely safe herb to take with no commonly known side effects or precautions for all ages