Erosion of the gastrointestinal wall by the ulcer leads to spillage of the stomach or intestinal contents into the abdominal cavity, leading to an acute chemical peritonitis. The first sign is often sudden intense abdominal pain, as seen in Valentinos syndrome. Posterior gastric wall perforation may lead to bleeding due to the involvement of gastroduodenal artery that lies posterior to the first part of the duodenum. The death rate in this case is 20%. Penetration is a form of perforation in which the hole leads to and the ulcer continues into adjacent organs such as the liver and pancreas. Gastric outlet obstruction (stenosis) is a narrowing of the pyloric canal by scarring and swelling of the gastric antrum and duodenum due to peptic ulcers. The person often presents with severe vomiting. Cancer is included in the differential diagnosis (elucidated by biopsy), Helicobacter pylori as the etiological factor making it 3 to 6 times more likely to develop stomach cancer from the ulcer. The risk for developing gastrointestinal cancer also appears to be slightly higher with gastric ulcers

Cause
H. pylori
Helicobacter pylori is one of the major causative factors of peptic ulcer disease. It secretes urease to create an alkaline environment, which is suitable for its survival. It expresses blood group antigen adhesin (BabA) and outer inflammatory protein adhesin (OipA), which enables it to attach to the gastric epithelium. The bacterium also expresses virulence factors such as CagA and PicB, which cause stomach mucosal inflammation.
In contrast to mirtazapine, the selective serotonin reuptake inhibitors (SSRI), serotonin–norepinephrine reuptake inhibitors (SNRI), Monoamine oxidase inhibitors (MAOI), and some Tricyclic antidepressants (TCA) increase the general activity of the 5-HT2A, 5-HT2C, and 5-HT3 receptors leading to a host of negative changes and side effects, the most prominent of which including anorexia, insomnia, nausea, and diarrhea, among others. Its reduced incidence of sexual dysfunction (such as loss of libido and anorgasmia) could be a product of negligible binding to the serotonin transporter (as is generally the cause of sexual dysfunction with most SSRIs) and antagonism of the 5-HT2A receptors; however, Mirtazapines high affinity towards and inverse agonism of the 5-HT2C receptors may greatly attenuate those pro-sexual factors (as evidenced by the pro-sexual effects of drugs like m-CPP and Lorcaserin which agonize 5-HT2C receptors in a reasonably selective manner). As a result, it is often combined with these drugs to reduce their side-effect profile and to produce a stronger antidepressant effect.Mirtazapine does not have pro-serotonergic activity and thus does not cause serotonin syndrome. This is in accordance with the fact that it is not a serotonin reuptake inhibitor or monoamine oxidase inhibitor (MAOI), nor a serotonin receptor agonist. There are no reports of serotonin syndrome in association with mirtazapine alone, and mirtazapine has not been found to cause serotonin syndrome in overdose. However, there are a handful of case reports of serotonin syndrome occurring with mirtazapine in combination with serotonergic drugs like SSRIs, although such reports are very rare, and do not necessarily implicate mirtazapine as causative.