Gastritis and H. pylori infection can be treated:

licorice root-clinically proven herbs for the treatment of ulcer and gastritis (highly active anti-inflammatory and inhibits in vitro growth of H. pylori), is not without risk so consult on the implementation with doctor, the basis of therapy
-Chamomile-anti-inflammatory and spazmolitic effect (apigenin in chamomile also inhibit Hp), as addition to treatment
-plants with mucus (flax, mallow root)-have a slightly anti-inflammatory effect. Mucus protect the stomach lining from irritation, again as a supplement
-marjoram, herb-regulates the secretion of gastric acid and has calming effect, additional
-ginger-just in case of nausea (may stimulate acid secretion, which is not objective)
-5g of vitamin C daily in more doses-destroys H.p. (clinically proven), in people with stomach ulcer and chronic gastritis vitamin C is in the stomach juice at low concentrations
-amino acid N-acetyl cysteine (NAC) helps in the treatment of atrophic gastritis (1-3g per day)
- extract of neema bark- lowers acid secretion, and in clinical testing has helped nearly all respondents in the healing of duodenal ulcer
-Tea tree essential oil-and ravensare (oral) may help in treating infections