Prohibited products are not permitted in the mail under any circumstances.
For more information visit /prohibitedgoods Prohibited items Please remember that Royal Mail also prohibits and restricts certain categories of items. Business customers are strongly recommended to do this. Specific restrictions and changes may be enforced at short notice, so for clarification please contact the destination country's trade, postal, and customs authorities as appropriate. The information below is provided in good faith, but Royal Mail is not responsible for it, and it should be viewed as a guide only. Prohibitions and restrictions vary from country to country, and can sometimes apply to items which you may think are ordinary. When an item is restricted you must comply with the restriction. You must not send any item addressed to a country in which the item is unlawful or prohibited. Please also refer to the Universal Postal Union - UPU - prohibitions and restrictions full list. For further information, or further clarification please refer to the Swiss Post website
Here is an indication of prohibited items for mailing to Switzerland.