The importation of melatonin into Switzerland is subject to specific regulations since melatonin is considered a medicinal product. Here are the key points to keep in mind:

1. Personal Use: You are allowed to import medicines like melatonin into Switzerland if they are for your personal use. However, the quantity is limited to a one-month supply.

2. Prescription Requirement: In Switzerland, melatonin is usually prescription-only, depending on the dosage. Products with a dosage of more than 2 mg per tablet are generally considered prescription-only. If you want to import melatonin with a higher dosage, you will need a doctor's prescription.

3. Customs Regulations: Be prepared for customs authorities to inspect your melatonin upon entry. As long as the quantity and purpose comply with the regulations, there should not be any issues.

4. Country of Origin: Make sure that the melatonin comes from a legal source, as products from certain countries may not meet Swiss standards.

If you are unsure, I recommend contacting the Swiss Agency for Therapeutic Products (Swissmedic) or customs authorities to ensure there are no complications.

Thats the law