Herbs that may be helpful: Three major categories of herbs are used to treat indigestion when no cause for the condition is known: bitters (digestive stimulants), carminatives (gas-relieving herbs), and demulcents (soothing herbs). The effects of these different categories on heartburn and low stomach acid will be discussed individually. Although there is overlap in the conditions, the categories are helpful.

Bitter herbs are thought to stimulate digestive function by increasing saliva production and promoting both stomach acid and digestive enzyme production.¹² As a result, they are particularly used when there is low stomach acid but not in heartburn (where too much stomach acid could initially exacerbate the situation). These herbs literally taste bitter. Some examples of bitter herbs include greater celandine, wormwood, and gentian. Bitters are generally taken either by mixing 1–3 ml tincture into water and sipping slowly 10–30 minutes before eating, or by making tea, which is also sipped slowly before eating.

A double-blind study found that a standardized extract of greater celandine could relieve symptoms of indigestion (such as abdominal cramping, sensation of fullness, and nausea) significantly better than placebo.¹³ The study employed an extract standardized to 4 mg of chelidonine per capsule and gave 1–2 tablets three times daily for six weeks. However, recent reports of hepatitis following intake of greater celandine have raised concerns about its safety for treating indigestion.¹⁴

Artichoke, in addition to being an edible plant, is a mild bitter. Extracts of artichoke have been repeatedly shown in double-blind research to be beneficial for people with indigestion.¹⁵ Artichoke is particularly useful when the problem is lack of bile production by the liver.¹⁶ Extracts providing 500–1,000 mg per day of cynarin, the main active constituent of artichoke, are recommended by doctors.

Wormwood is sometimes used in combination with carminative herbs for people with indigestion. One double-blind trial found that a combination with peppermint, caraway, and fennel was useful in reducing gas and cramping in people with indigestion.¹⁷ Other bitters are gentian, dandelion, blessed thistle, yarrow, devil’s claw, bitter orange, bitter melon, juniper, andrographis, prickly ash, and centaury.¹⁸ The amounts used are the same as the general recommendations for bitters when they are employed for the treatment of indigestion.

Some bitters widely used in traditional medicine in North America include yarrow, yellow dock, goldenseal, Oregon grape, and vervain. Oregon grape’s European cousin barberry has also traditionally been used as a bitter. Animal studies indicate that yarrow, barberry, and Oregon grape, in addition to stimulating digestion like other bitters, may relieve spasms in the intestinal tract.¹⁹

Boldo has been used in South America for a variety of digestive conditions, although this may have stemmed from its impact on intestinal infections or liver function. Studies specifically showing a benefit from taking boldo in people with indigestion and heartburn have not been performed. Picrorhiza, from India, has a similar story to that of boldo. While it is clearly a bitter digestive stimulant, human studies to confirm this have not yet been completed.

Horehound contains a number of constituents, including alkaloids, flavonoids, diterpenes (e.g., marrubiin), and trace amounts of volatile oils.²⁰ The major active constituent marrubiin and possibly its precursor, premarrubiin, are herbal bitters that increase the flow of saliva and gastric juice, thereby stimulating the appetite.²¹ Similar to horehound, elecampane has been used by herbalists to treat people with indigestion.

Carminatives (also called aromatic digestive tonics or aromatic bitters) may be used to relieve symptoms of indigestion, particularly when there is excessive gas. It is believed that carminative agents work, at least in part, by relieving spasms in the intestinal tract.²²

Among the most notable and well-studied carminatives are peppermint, fennel, and caraway. Double-blind trials have shown that combinations of peppermint and caraway oil and a combination of peppermint, fennel, caraway, and wormwood have been found to reduce gas and cramping in people with indigestion.^{23 24 25} Generally, 3–5 drops of natural essential oils or 3–5 ml of tincture of any of these herbs, taken in water two to three times per day before meals, can be helpful. Alternately, a tea can be made by grinding 2–3 teaspoons of the seeds of fennel or caraway or the leaves of peppermint, and then simmering them in a cup of water (covered) for ten minutes. Drink three or more cups per day just after meals.

Linden also has a long tradition of use for indigestion. Older clinical trials have shown that linden flower tea can help people who suffer from upset stomach or from excessive gas that causes the stomach to push up and put pressure on the heart (also known as the gastrocardiac syndrome.)^{26 27} The reputed antispasmodic action of linden, particularly in the intestines, has been confirmed in at least one human trial.²⁸ Linden tea is prepared by steeping 2–3 tsp of flowers in a cup of hot water for 15 minutes. Several cups per day are recommended.

In a double-blind trial, the spice turmeric was found to relieve indigestion.²⁹ Two capsules containing 250 mg turmeric powder per capsule were given four times per day.

Chamomile (German chamomile or Matricaria recutita) is effective in relieving inflamed or irritated mucous membranes of the digestive tract. Since heartburn sometimes involves reflux of stomach acid into the esophagus, the anti-inflammatory properties of chamomile may also be useful. In addition, chamomile promotes normal digestion.³⁰ However, modern studies to prove chamomile beneficial for people with heartburn or indigestion are lacking. Roman chamomile (Anthemis nobilis) has not been studied for indigestion though it has traditionally been used similarly to German chamomile.

Typically taken in tea form, chamomile is recommended three to four times per day between meals. Chamomile tea is prepared by pouring boiling water over dried flowers, and steeping for several minutes. Alternatively, 3–5 ml of chamomile tincture may be added to hot water or 2–3 grams of chamomile in capsule or tablet form may be taken three to four times per day between meals.

Lemon balm is another carminative herb used traditionally for indigestion.³¹ Lemon balm, usually taken as tea, is prepared by steeping 2–3 teaspoons of leaves in hot water for 10 to 15 minutes in a covered container. Three or more cups per day are consumed immediately after meals. Three to five milliliters of tincture can also be used three times per day.

There are numerous other carminative herbs, including European angelica root (Angelica archangelica), anise, Basil, cardamom, cinnamon, cloves, coriander, dill, ginger, oregano, rosemary, sage, lavender, and thyme.³² Many of these are common kitchen herbs and thus are readily available for making tea to calm an upset stomach. Rosemary is sometimes used to treat indigestion in the elderly by European herbal practitioners.³³ The German Commission E monograph suggests a daily intake of 4–6 grams of sage leaf.³⁴ Pennyroyal is no longer recommended for use in people with indigestion, however, due to potential side effects.

Demulcents are the third category of herbs used to treat indigestion and heartburn. These herbs seem to work by decreasing inflammation and forming a physical barrier against stomach acid or other abdominal irritants. Examples of demulcent herbs include ginger, licorice, and slippery elm.

Ginger is a spice well known for its traditional use as a treatment for a variety of gastrointestinal complaints, ranging from flatulence to ulcers. Ginger has anti-inflammatory and anti-nausea properties. Ginger has been shown to enhance normal, spontaneous movements of the intestines that aid digestion.³⁵

Licorice protects the mucous membranes lining the digestive tract by increasing the production of mucin, a compound that protects against the adverse effects of stomach acid and various harmful substances.³⁶ The extract of licorice root that is most often used by people with indigestion is known as deglycyrrhizinated licorice (DGL). Glycyrrhizin, which occurs naturally in licorice root, has cortisone-like effects and can cause high blood pressure, water retention, and other problems in some people. When the glycyrrhizin is removed to form DGL, the licorice root retains its beneficial effects against indigestion, while the risk of side effects is greatly reduced. The usual suggested amount of DGL is one or two chewable tablets (250–500 mg per tablet), chewed and swallowed 15 minutes before meals and one to two hours before bedtime.³⁷ Although many research trials show that DGL is helpful for people with peptic ulcers, the use of DGL for heartburn and indigestion is based primarily on anecdotal information.

The mucilage content in slippery elm appears to act as a barrier against the damaging effects of acid on the esophagus in people with heartburn. It may also have an anti-inflammatory effect locally in the stomach and intestines. Two or more tablets or capsules (typically 400–500 mg each) may be taken three to four times per day. Alternatively, a tea is made by boiling 1/2–2 grams of the bark in 200 ml of water for 10 to 15 minutes, which is then cooled before drinking; three to four cups a day can be used. Tincture (5 ml three times per day) may also be taken but is believed to be less helpful. Marshmallow and bladderwrack may be used the same way as slippery elm.

People in the southwestern United States and northern Mexico have long used chaparral tea to help calm upset stomachs. It is unclear into which of the above categories—if any—chaparral fits. This strong tasting tea was used only in small amounts. Modern research has not confirmed the usefulness of chaparral for indigestion, and there are serious concerns about the safety of improper internal use of this herb. Before taking chaparral, consult with a knowledgeable healthcare professional.