If the receiving partner has wounds on their genitals, or if the giving partner has wounds or open sores on or in their mouth, or bleeding gums, this poses an increased risk of STD transmission. Brushing the teeth, flossing, undergoing dental work, or eating crunchy foods such as potato crisps relatively soon before or after giving fellatio can also increase the risk of transmission, because all of these activities can cause small scratches in the lining of the mouth. These wounds, even when they are microscopic, increase the chances of contracting STDs that can be transmitted orally under these conditions. Such contact can also lead to more mundane infections from common bacteria and viruses found in, around and secreted from the genital regions. Because of this, some medical professionals advise the use of condoms when performing or receiving fellatio with a partner whose STD status is unknown. Flavoured condoms may be used for this purpose.