with side effects. zanamivir or oseltamivir decrease the chance that people who are exposed to the virus will develop symptoms; however, it is recommended that potential side effects are taken into account. other smoking cessation and reducing indoor air pollution, such as that from cooking indoors with wood, crop residues or dung, are both recommended. smoking appears to be the single biggest risk factor for pneumococcal pneumonia in otherwise-healthy adults. hand hygiene and coughing into one's sleeve may also be effective preventative measures. wearing surgical masks by the sick may also prevent illness. appropriately treating underlying illnesses (such as hiv/aids, diabetes mellitus, and malnutrition) can decrease the risk of pneumonia. in children less than 6 months of age, exclusive breast feeding reduces both the risk and severity of disease. in people with hiv/aids and a cd4 count of less than 200 cells/ul the antibiotic trimethoprim/sulfamethoxazole decreases the risk of pneumocystis pneumonia and is also useful for prevention in those that are immunocompromised but do not have hiv. testing pregnant women for group b streptococcus and chlamydia trachomatis, and administering antibiotic treatment, if needed, reduces rates of pneumonia in infants; preventive measures for hiv transmission from mother to child may also be efficient. suctioning the mouth and throat of infants with meconium-stained amniotic fluid has not been found to reduce the rate of aspiration pneumonia and may cause potential harm, thus this practice is not recommended in the majority of situations. in the frail elderly good oral health care may lower the risk of aspiration pneumonia, even though there is no good evidence that one approach to mouth care is better than others in preventing nursing home acquired pneumonia. zinc supplementation in children 2 months to five years old appears to reduce rates of pneumonia. for people with low levels of vitamin c in their diet or blood, taking vitamin c supplements may be suggested to decrease the risk of pneumonia, although there is no strong evidence of benefit. there is insufficient evidence to recommend that the general population take vitamin c to prevent or treat pneumonia. for adults and children in the hospital who require a respirator, there is no strong evidence indicating a difference between heat and moisture exchangers and heated humidifiers for preventing pneumonia. there is tentative evidence that laying flat on the back compared to semi-raised increases pneumonia risks in people who are intubated. management curb-65 symptompoints confusion1 urea>7 mmol/l1 respiratory rate>301 sbp<90mmhg, dbp<60mmhg1 age>=651 antibiotics by mouth, rest, simple analgesics, and fluids usually suffice for complete resolution. however, those with other medical conditions, the elderly, or those with significant trouble breathing may require more advanced care. if the symptoms worsen, the pneumonia does not improve with home treatment, or complications occur, hospitalization may be required. worldwide, approximately 7–13% of cases in children result in hospitalization, whereas in the developed world between 22 and 42% of adults with community-acquired pneumonia are admitted. the curb-65 score is useful for determining the need for admission in adults. if the score is 0 or 1, people can typically be managed at home; if it is 2, a short hospital stay or close follow-up is needed; if it is 3–5, hospitalization is recommended. in children those with respiratory distress or oxygen saturations of less than 90% should be hospitalized. the utility of chest physiotherapy in pneumonia has not yet been determined. over-the-counter cough medicine has not been found to be effective, nor has the use of zinc supplementation in children. there is insufficient evidence for mucolytics. there is no strong evidence to recommend that children who have non-measles related pneumonia take vitamin a supplements. vitamin d, as of 2018 is of unclear benefit in children. vitamin c administration in pneumonia needs further research, although it can be given to patient of low plasma vitamin c because it is not expensive and low risk. pneumonia can cause severe illness in a number of ways, and pneumonia with evidence of organ dysfunction may require intensive care unit admission for observation and specific treatment. the main impact is on the respiratory and the circulatory system. respiratory failure not responding to normal oxygen therapy may require heated humidified high-flow therapy delivered through nasal cannulae, non-invasive ventilation, or in severe cases mechanical ventilation through an endotracheal tube. regarding circulatory problems as part of sepsis, evidence of poor blood flow or low blood pressure is initially treated with 30 ml/kg of crystalloid infused intravenously. in situations where fluids alone are ineffective, vasopressor medication may be required. for adults with moderate or severe acute respiratory distress syndrome (ards) undergoing mechanical ventilation, there is a reduction in mortality when people lie on their front for at least 12 hours a day. however, this increases the risk of endotracheal tube obstruction and pressure sores. bacterial antibiotics improve outcomes in those with bacterial pneumonia. the first dose of antibiotics should be given as soon as possible. increased use of antibiotics, however, may lead to the development of antimicrobial resistant strains of bacteria. antibiotic choice depends initially on the characteristics of the person affected, such as age, underlying health, and the location the infection was acquired. antibiotic use is also associated with side effects such as nausea, diarrhea, dizziness, taste distortion, or headaches. in the uk, treatment before culture results with amoxicillin is recommended as the first line for community-acquired pneumonia, with doxycycline or clarithromycin as alternatives. in north america, amoxicillin, doxycycline, and in some areas a macrolide (such as azithromycin or erythromycin) is the first-line outpatient treatment in adults. in children with mild or moderate symptoms, amoxicillin taken by mouth is the first line. the use of fluoroquinolones in uncomplicated cases is discouraged due to concerns about side-effects and generating resistance in light of there being no greater benefit. for those who require hospitalization and caught their pneumonia in the community the use of a β-lactam such as cephazolin plus a macrolide such as azithromycin is recommended. a fluoroquinolone may replace azithromycin but is less preferred. antibiotics by mouth and by injection appear to be similarly effective in children with severe pneumonia. the duration of treatment has traditionally been seven to ten days, but increasing evidence suggests that shorter courses (3–5 days) may be effective for certain types of pneumonia and may reduce the risk of antibiotic resistance. research in children showed that a shorter, 3-day course of amoxicillin was as effective as a longer, 7-day course for treating pneumonia in this population. for pneumonia that is associated with a ventilator caused by non-fermenting gram-negative bacilli (nf-gnb), a shorter course of antibiotics increases the risk that the pneumonia will return. recommendations for hospital-acquired pneumonia include third- and fourth-generation cephalosporins, carbapenems, fluoroquinolones, aminoglycosides, and vancomycin. these antibiotics are often given intravenously and used in combination. in those treated in hospital, more than 90% improve with the initial antibiotics. for people with ventilator-acquired pneumonia, the choice of antibiotic therapy will depend on the person's risk of being infected with a strain of bacteria that is multi-drug resistant. once clinically stable, intravenous antibiotics should be switched to oral antibiotics. for those with methicillin resistant staphylococcus aureus (mrsa) or legionella infections, prolonged antibiotics may be beneficial. the addition of corticosteroids to standard antibiotic treatment appears to improve outcomes, reducing death and morbidity for adults with severe community acquired pneumonia, and reducing death for adults and children with non-severe community acquired pneumonia. a 2017 review therefore recommended them in adults with severe community acquired pneumonia. a 2019 guideline however recommended against their general use, unless refractory shock was present. side effects associated with the use of corticosteroids include high blood sugar. there is some evidence that adding corticosteroids to the standard pcp pneumonia treatment may be beneficial for people who are infected with hiv. the use of granulocyte colony stimulating factor (g-csf) along with antibiotics does not appear to reduce mortality and routine use for treating pneumonia is not supported by evidence. viral neuraminidase inhibitors may be used to treat viral pneumonia caused by influenza viruses (influenza a and influenza b). no specific antiviral medications are recommended for other types of community acquired viral pneumonias including sars coronavirus, adenovirus, hantavirus, and parainfluenza virus. influenza a may be treated with rimantadine or amantadine, while influenza a or b may be treated with oseltamivir, zanamivir or peramivir. these are of most benefit if they are started within 48 hours of the onset of symptoms. many strains of h5n1 influenza a, also known as avian influenza or "bird flu", have shown resistance to rimantadine and amantadine. the use of antibiotics in viral pneumonia is recommended by some experts, as it is impossible to rule out a complicating bacterial infection. the british thoracic society recommends that antibiotics be withheld in those with mild disease. the use of corticosteroids is controversial. aspiration in general, aspiration pneumonitis is treated conservatively with antibiotics indicated only for aspiration pneumonia. the choice of antibiotic will depend on several factors, including the suspected causative organism and whether pneumonia was acquired in the community or developed in a hospital setting. common options include clindamycin, a combination of a beta-lactam antibiotic and metronidazole, or an aminoglycoside. corticosteroids are sometimes used in aspiration pneumonia, but there is limited evidence to support their effectiveness. follow-up the british thoracic society recommends that a follow-up chest radiograph be taken in people with persistent symptoms, smokers, and people older than 50. american guidelines vary, from generally recommending a follow-up chest radiograph to not mentioning any follow-up. prognosis with treatment, most types of bacterial pneumonia will stabilize in 3–6 days. it often takes a few weeks before most symptoms resolve. x-ray findings typically clear within four weeks and mortality is low (less than 1%). in the elderly or people with other lung problems, recovery may take more than 12 weeks. in persons requiring hospitalization, mortality may be as high as 10%, and in those requiring intensive care it may reach 30–50%. pneumonia is the most common hospital-acquired infection that causes death. before the advent of antibiotics, mortality was typically 30% in those that were hospitalized. however, for those whose lung condition deteriorates within 72 hours, the problem is usually due to sepsis. if pneumonia deteriorates after 72 hours, it could be due to nosocomial infection or excerbation of other underlying comorbidities. about 10% of those discharged from hospital are readmitted due to underlying co-morbidities such as heart, lung, or neurological disorders, or due to new onset of pneumonia. complications may occur in particular in the elderly and those with underlying health problems. this may include, among others: empyema, lung abscess, bronchiolitis obliterans, acute respiratory distress syndrome, sepsis, and worsening of underlying health problems. clinical prediction rules clinical prediction rules have been developed to more objectively predict outcomes of pneumonia. these rules are often used to decide whether to hospitalize the person. curb-65 score, which takes into account the severity of symptoms, any underlying diseases, and age pneumonia severity index (or psi score) pleural effusion, empyema, and abscess a pleural effusion: as seen on chest x-ray. the a arrow indicates fluid layering in the right chest. the b arrow indicates the width of the right lung. the volume of the lung is reduced because of the collection of fluid around the lung. in pneumonia, a collection of fluid may form in the space that surrounds the lung. occasionally, microorganisms will infect this fluid, causing an empyema. to distinguish an empyema from the more common simple parapneumonic effusion, the fluid may be collected with a needle (thoracentesis), and examined. if this shows evidence of empyema, complete drainage of the fluid is necessary, often requiring a drainage catheter. in severe cases of empyema, surgery may be needed. if the infected fluid is not drained, the infection may persist, because antibiotics do not penetrate well into the pleural cavity. if the fluid is sterile, it must be drained only if it is causing symptoms or remains unresolved. in rare circumstances, bacteria in the lung will form a pocket of infected fluid called a lung abscess. lung abscesses can usually be seen with a chest x-ray but frequently require a chest ct scan to confirm the diagnosis. abscesses typically occur in aspiration pneumonia, and often contain several types of bacteria. long-term antibiotics are usually adequate to treat a lung abscess, but sometimes the abscess must be drained