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Concept: Cough medicine


Dextromethorphan (3-methoxy-N-methylmorphinan), also known as “DXM” and “the poor man’s PCP,” is a synthetically produced drug that is available in more than 140 over-the-counter cough and cold preparations. Dextromethorphan (DXM) has overtaken codeine as the most widely used cough suppressant due to its availability, efficacy, and safety profile at directed doses. However, DXM is subject to abuse. When consumed at inappropriately high doses (over 1500 mg/day), DXM can induce a state of psychosis characterized by Phencyclidine (PCP)-like psychological symptoms, including delusions, hallucinations, and paranoia. We report a noteworthy case of severe dextromethorphan use disorder with dextromethorphan-induced psychotic disorder in a 40-year-old Caucasian female, whose symptoms remitted only following treatment with a combination of an antipsychotic and mood stabilizer. While some states have begun to limit the quantity of DXM sold or restrict sales to individuals over 18-years of age, there is currently no federal ban or restriction on DXM. Abuse of DXM, a readily available and typically inexpensive agent that is not detected on a standard urine drug screen, may be an under-recognized cause of substance-induced psychosis. It is imperative that clinicians are aware of the potential psychiatric sequelae of recreational DXM use.

Concepts: Cough, Schizophrenia, Psychosis, Bipolar disorder, Psychiatry, Common cold, Codeine, Cough medicine


Background: Currently available over-the-counter cough remedies historically have been criticized for lack of scientific evidence supporting their efficacy. Although the first-generation antihistamine diphenhydramine is classified as an antitussive by the United States Food and Drug Administration, to the authors' knowledge it has never been shown to inhibit cough reflex sensitivity in subjects with pathological cough. Objective: To evaluate the effect of diphenhydramine on cough reflex sensitivity. Setting: Montefiore Medical Center, an academic medical center in New York City. Methods: Twenty two subjects with acute viral upper respiratory tract infection (common cold) underwent cough reflex sensitivity measurement employing capsaicin challenge on 3 separate days, 2 h after ingesting single doses of study drug (to coincide with peak blood concentrations), administered in randomized, double-blind manner: a multicomponent syrup containing diphenhydramine (25 mg), phenylephrine (10 mg), in a natural cocoa formulation; dextromethorphan (30 mg) syrup; and, placebo syrup. The standard endpoint of cough challenge was used: concentration of capsaicin inducing ≥5 coughs (C5). Main outcome measure: Effect on cough reflex sensitivity (C5). Results: A significant difference (p = 0.0024) was established among groups, with pairwise analysis revealing a significant increase in mean log C5 (0.4 ± 0.55 (SD); p < 0.01) for the diphenhydramine-containing medication versus placebo, but not for dextromethorphan versus placebo. Conclusions: Our results provide the initial evidence of the ability of diphenhydramine to inhibit cough reflex sensitivity in subjects with acute pathological cough. Timing of cough reflex sensitivity measurement may not have allowed demonstration of maximal antitussive effect of dextromethorphan.

Concepts: Cough, Respiratory system, Upper respiratory tract, Upper respiratory tract infection, Lower respiratory tract, Common cold, Codeine, Cough medicine


Codeine-containing cough syrups have become one of the most popular drugs of abuse in young people in the world. Chronic codeine-containing cough syrup abuse is related to impairments in a broad range of cognitive functions. However, the potential brain white matter impairment caused by chronic codeine-containing cough syrup abuse has not been reported previously. Our aim was to investigate abnormalities in the microstructure of brain white matter in chronic users of codeine-containing syrups and to determine whether these WM abnormalities are related to the duration of the use these syrups and clinical impulsivity.

Concepts: Psychology, Matter, Cognition, Mind, Common cold, Recreational drug use, Cough medicine, Purple drank


Dextromethorphan is a safe, effective cough suppressant, available without a prescription in the United States since 1958. Due to a perceived prevalence of abuse of dextromethorphan by teens, in 2007 the Drug Enforcement Administration requested the Food and Drug Administration evaluate whether dextromethorphan should be recommended for scheduling under the Controlled Substances Act. The Food and Drug Administration held an Advisory Committee meeting in 2010 to provide a scientific and medical evaluation of dextromethorphan and its abuse potential.

Concepts: Cough, United States, Controlled Substances Act, Food and Drug Administration, Latin, Codeine, Drug Enforcement Administration, Cough medicine


There is little evidence that the decongestant, antihistamine, or cough suppressant medications commonly used to treat cold symptoms in preschool children are effective. One option for treating cold symptoms in young children is with homeopathy. This study was conducted to determine if a homeopathic syrup was effective in treating cold symptoms in preschool children.

Concepts: Pharmacology, Cough, Randomized controlled trial, Placebo, Alternative medicine, Common cold, Homeopathy, Cough medicine


Acute cough associated with the common cold (CACC) causes significant impairment in quality of life. Effective treatment approaches are needed for CACC. We conducted a systematic review on the management of CACC to update the recommendations and suggestions of the CHEST 2006 guideline on this topic.

Concepts: Asthma, Cough, Common cold, Dextromethorphan, Cough medicine


The modulation of cough by microinjections of codeine in 3 medullary regions, the solitary tract nucleus rostral to the obex (rNTS), caudal to the obex (cNTS) and the lateral tegmental field (FTL) was studied. Experiments were performed on 27 anesthetized spontaneously breathing cats. Electromyograms (EMG) were recorded from the sternal diaphragm and expiratory muscles (transversus abdominis and/or obliquus externus; ABD). Repetitive coughing was elicited by mechanical stimulation of the intrathoracic airways. Bilateral microinjections of codeine (3.3 or 33mM, 54±16nl per injection) in the cNTS had no effect on cough, while those in the rNTS and in the FTL reduced coughing. Bilateral microinjections into the rNTS (3.3mM codeine, 34±1 nl per injection) reduced the number of cough responses by 24% (P<0.05), amplitudes of diaphragm EMG by 19% (P<0.01), of ABD EMG by 49% (P<0.001) and of expiratory esophageal pressure by 56% (P<0.001). Bilateral microinjections into the FTL (33mM codeine, 33±3 nl per injection) induced reductions in cough expiratory as well as inspiratory EMG amplitudes (ABD by 60% and diaphragm by 34%; P<0.01) and esophageal pressure amplitudes (expiratory by 55% and inspiratory by 26%; P<0.001 and 0.01, respectively). Microinjections of vehicle did not significantly alter coughing. Breathing was not affected by microinjections of codeine. These results suggest that: 1) codeine acts within the rNTS and the FTL to reduce cough in the cat, 2) the neuronal circuits in these target areas have unequal sensitivity to codeine and/or they have differential effects on spatiotemporal control of cough, 3) the cNTS has a limited role in the cough suppression induced by codeine in cats.

Concepts: Neuroanatomy, Cough, Transversus abdominis muscle, Gastroesophageal reflux disease, Cat, Iliac crest, Codeine, Cough medicine


A 25-year-old college student with no medical history sought care at our hospital for a nonproductive cough, subjective fevers, myalgia, and malaise that he’d developed 10 days earlier. The day before his visit, he’d also developed scratchy red eyes and a sore throat. He said he’d taken an over-the-counter cough suppressant to help with the cough, but his eyes and lips developed further redness and irritation. On examination, the patient demonstrated conjunctival suffusion, periorbital edema, diffuse oral stomatitis with pseudomembranous crusting, and nasal crusting. His vital signs were within normal limits, and he had no epithelial skin eruptions or erosions in any other mucosal regions. What’s your diagnosis?

Concepts: HIV, Inflammation, Patient, Influenza, Eye puffiness, Common cold, Codeine, Cough medicine


Post-infectious cough is a common symptom associated with common colds and/or upper respiratory tract infection. This cough is expected to last for only for few days and resolve spontaneously, whilst when persists for longer than three weeks is defined “persistent” and is associated tickling or an irritating sensation in the throat which often leads to paroxysms of coughing. Persistent post-infectious cough can cause morbidity since it may interfere with usual living. Despite the recent advances in understanding the mechanisms that regulate cough, in physiological and pathological conditions, current therapeutic options for post-infectious cough are little or only moderately effective.

Concepts: Asthma, Cough, Respiratory system, Upper respiratory tract, Upper respiratory tract infection, Common cold, Dextromethorphan, Cough medicine


Chronic cough is a significant problem and in many patients' cough remains refractive to both disease specific therapies and current cough suppressing medicines, creating a need for improved anti-tussive therapies. Most patients with chronic cough also display heightened sensitivity such that they experience a persistent sense of the need to cough and often innocuous stimuli can trigger their coughing. This hypersensitivity underpins the newly described concept of Cough Hypersensitivity Syndrome (CHS), a term that encapsulates the notion of common underlying mechanisms producing neuronal activation, sensitization and/or dysfunction, which are at the core of excessive coughing. Understanding these mechanisms has been a focus of recent research efforts in the field in the hope that new therapies can be developed to selectively target sensitized unproductive cough whilst maintaining the reflexive cough essential for airway protection. However, efforts to achieve this have been slower than expected, in part because of some significant challenges and limitations translating current cough models. In this review, we will summarize recent advances in our understanding of the sensory circuits innervating the respiratory system important for cough, how cough sensory pathways become hypersensitive, and some of the recently described neural targets under development for treating chronic coughing. We will present the case that better use of current cough models and/ or the development of new models is ultimately needed to advance our efforts to translate the discovery of basic cough mechanisms into effective medicines for treating patients with chronic cough.

Concepts: Medicine, Asthma, Cough, Hypersensitivity, Respiratory system, Common cold, Codeine, Cough medicine