An antiflatulent agent is a drug used for the alleviation or prevention of excessive intestinal gas, i.e., flatulence

Flatulence

Flatulence is the expulsion through the rectum of a mixture of gases that are byproducts of the digestion process of mammals and other animals. The medical term for the mixture of gases is flatus, informally known as a fart, or simply gas...

.

Preventing gas

• Enzymes - Enzyme
  Enzyme
  Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...
  
  -based dietary supplement
  Dietary supplement
  A dietary supplement, also known as food supplement or nutritional supplement, is a preparation intended to supplement the diet and provide nutrients, such as vitamins, minerals, fiber, fatty acids, or amino acids, that may be missing or may not be consumed in sufficient quantities in a person's diet...
  
  s break down indigestible substances and prevent these substances from reaching the large intestine intact -- where anaerobic bacteria produce gas. Substances indigestible by humans are usually present in foods associated with flatulence, like beans. When these substances reach the large intestine
  Large intestine
  The large intestine is the third-to-last part of the digestive system — — in vertebrate animals. Its function is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body...
  
   intact, they may be fermented by intestinal bacteria
  Bacteria
  Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
  
  , thereby causing gas production. These supplements are usually taken with foods associated with flatulence. It is important to take the appropriate enzyme with the appropriate food. When consuming bean
  Bean
  Bean is a common name for large plant seeds of several genera of the family Fabaceae used for human food or animal feed....
  
  s and other vegetables high in complex carbohydrates, it may be helpful to take a product that contains alpha-galactosidase
  Alpha-galactosidase
  Alpha-galactosidase is a glycoside hydrolase enzyme that hydrolyses the terminal alpha-galactosyl moieties from glycolipids and glycoproteins. It is encoded by the gene.- Function :...
  
  , such as Beano
  Beano (dietary supplement)
  Beano is an enzyme-based dietary supplement that is used to reduce gas in the digestive tract, thereby improving digestion and reducing bloating, discomfort, and flatulence caused by gas. It contains the enzyme alpha galactosidase that breaks down oligosaccharides such as raffinose...
  
  . Additionally, for individuals with lactose intolerance
  Lactose intolerance
  Lactose intolerance, also called lactase deficiency or hypolactasia, is the inability to digest and metabolize lactose, a sugar found in milk...
  
  , taking a lactase
  Lactase
  Lactase , a part of the β-galactosidase family of enzymes, is a glycoside hydrolase involved in the hydrolysis of the disaccharide lactose into constituent galactose and glucose monomers...
  
  -containing product with lactose
  Lactose
  Lactose is a disaccharide sugar that is found most notably in milk and is formed from galactose and glucose. Lactose makes up around 2~8% of milk , although the amount varies among species and individuals. It is extracted from sweet or sour whey. The name comes from or , the Latin word for milk,...
  
  -containing foodstuffs may reduce flatulence.

• Herbal Inhibitors -- Many herbal substances have been observered since antiquity for reducing flatulence, particularly gas from eating legumes. Cloves, cinnamon
  Cinnamon
  Cinnamon is a spice obtained from the inner bark of several trees from the genus Cinnamomum that is used in both sweet and savoury foods...
  
  , and garlic
  Garlic
  Allium sativum, commonly known as garlic, is a species in the onion genus, Allium. Its close relatives include the onion, shallot, leek, chive, and rakkyo. Dating back over 6,000 years, garlic is native to central Asia, and has long been a staple in the Mediterranean region, as well as a frequent...
  
   are potent in reducing gas. The potency of garlic increases when heated, whereas the potency of cinnamon decreases. Other spices have a smaller effect in reducing gas, including turmeric
  Turmeric
  Turmeric is a rhizomatous herbaceous perennial plant of the ginger family, Zingiberaceae. It is native to tropical South Asia and needs temperatures between 20 °C and 30 °C and a considerable amount of annual rainfall to thrive...
  
  , black pepper
  Black pepper
  Black pepper is a flowering vine in the family Piperaceae, cultivated for its fruit, which is usually dried and used as a spice and seasoning. The fruit, known as a peppercorn when dried, is approximately in diameter, dark red when fully mature, and, like all drupes, contains a single seed...
  
  , asafoetida
  Asafoetida
  Asafoetida , alternative spelling asafetida, is the dried latex exuded from the living underground rhizome or tap root of several species of Ferula, which is a perennial herb...
  
   and ginger
  Ginger
  Ginger is the rhizome of the plant Zingiber officinale, consumed as a delicacy, medicine, or spice. It lends its name to its genus and family . Other notable members of this plant family are turmeric, cardamom, and galangal....
  
  . Other common Indian spices, cumin
  Cumin
  Cumin is a flowering plant in the family Apiaceae, native from the east Mediterranean to India. Its seeds are used in the cuisines of many different cultures, in both whole and ground form.-Etymology:...
  
  , aniseed, ajowan, and cardamom
  Cardamom
  Cardamom refers to several plants of the genera Elettaria and Amomum in the ginger family Zingiberaceae. Both genera are native to India and Bhutan; they are recognised by their small seed pod, triangular in cross-section and spindle-shaped, with a thin papery outer shell and small black seeds...
  
   do not inhibit gas production.

Relieving gas

For the alleviation of flatulence, an antifoaming agent such as simethicone

Simethicone

Simethicone is an oral anti-foaming agent used to reduce bloating, discomfort and pain caused by excess gas in the stomach or intestinal tract. It is a mixture of polydimethylsiloxane and silica gel.-Chemical action and pharmaceutical effects:...

 may be taken orally. This agent will coalesce the smaller gas bubbles into larger bubbles, thereby easing the release of gas within the gastrointestinal tract

Gastrointestinal tract

The human gastrointestinal tract refers to the stomach and intestine, and sometimes to all the structures from the mouth to the anus. ....

 via burping

Burping

Belching involves the release of gas from the digestive tract through the mouth. It is usually accompanied with a typical sound and, at times, an odor...

 or flatulence.

Enzyme-based dietary supplements

• Beano
  Beano (dietary supplement)
  Beano is an enzyme-based dietary supplement that is used to reduce gas in the digestive tract, thereby improving digestion and reducing bloating, discomfort, and flatulence caused by gas. It contains the enzyme alpha galactosidase that breaks down oligosaccharides such as raffinose...
  
  
• Lactase
  Lactase
  Lactase , a part of the β-galactosidase family of enzymes, is a glycoside hydrolase involved in the hydrolysis of the disaccharide lactose into constituent galactose and glucose monomers...
  
   (brand Lactaid)

Herbal antiflatulents

• Epazote
  Epazote
  Epazote, wormseed, Jesuit's tea, Mexican tea, Paico or Herba Sancti Mariæ is an herb native to Central America, South America, and southern Mexico....
  
   is claimed to have antiflatulent properties.
• Asafoetida
  Asafoetida
  Asafoetida , alternative spelling asafetida, is the dried latex exuded from the living underground rhizome or tap root of several species of Ferula, which is a perennial herb...
  
  reduces the growth of indigenous microflora in the gut, reducing flatulence.