Never take more than the recommend dosage of 2 grams per sitting, or 5 grams a day. Doing so can result in dizziness and nausea. Swallowing betel nut can result in an upset stomach, as well as diarrhoea.
Long term use of betel nut can stain the teeth a reddish black colour and can also result in mild addiction and excess saliva production. The use of betel nut has been linked to increased risk of oral cancer.