All food is medicine and there is only a problem when foods are used in extreme amounts. The best diet is one which contains many colours, varieties and textures to provide the whole spectrum of essential life giving nutrients, vitamins, minerals and proteins. I suggest to continue using chilli/ cayenne in your cooking and remember that many foods if used unappropriately can cause damage to the body. The following statement I believe sums it up perfectly small amounts stimulate, medium amounts inhibit and large amounts kill.
Cayenne has been used to reduce inflammation present in the body, increase circulation, prevent blood clotting, kill off detrimental digestive microflora, bacteria and moulds, helps to lower serum cholesterol levels, pain relief, inhibits bronchoconstriction in asthmatics and is a decongestant for the lymphatic and respiratory systems . The only contraindication with using Cayenne is when you have a gout related inflammatory condition. This is due to Cayenne being a member of the deadly nightshade family of foods which greatly contribute to the production of uric acid thereby promoting inflammation.
If you dig deep enough you will always find controversial information regarding the effectiveness or adverse effects of many herbs. It is a difficult situation but if we look historically and traditionally at the usage of Cayenne pepper for culinary and medical purposes it receives far more positive testimonials than negative ones.
Due to the heat that Cayenne expels when digested it may cause trouble with the lining of the digestive system which in turn will increase inflammation and degradation of the mucus membrane of the linings of the digestive system and which may lead to ulcers. However, this is generally only experienced when it is taken in large amounts and on an empty stomach. There are many studies which suggest the opposite in relation to using Cayenne for the symptoms of arthritis and inflammation.