It has effects similar to the phenothiazines. Specific examples include anticholinergics, diuretics, phenothiazines and barbiturates. Low blood pressure caused by phenothiazines, hypertension, and pheochromocytoma. These antagonists include first generation (typical) antipsychotics such as butyrophenones, phenothiazines, and thioxanthenes. Trismus can be seen as an extra-pyramidal side-effect of metoclopromide, phenothiazines and other medications. Phenothiazines&colon; Particularly effective in treating opioid-induced PONV. Succinyl choline, phenothiazines and tricyclic antidepressants causes trismus as a secondary effect. The term "phenothiazines" describes the largest of the five main classes of antipsychotic drugs. Most conventional antipsychotics, such as the phenothiazines, work by blocking the D2 Dopamine receptors. Its chemical structure closely resembles the phenothiazines, tricyclic antidepressants, and clonidine. The central CSN ring is folded in phenothiazines. The thioxanthenes, as a class, are closely related chemically to the phenothiazines. Few pharmaceutically significant phenothiazines are prepared from phenothiazine, although some of them are. It is a rare extrapyramidal side effect of phenothiazines, haloperidol, and metoclopramide. These medicines are also effective after nausea develops, as are phenothiazines.