The recommendations are consistent with those made by the British Thoracic Society in Recommendations for the management of cough in adults [Morice et al, 2006].

• Analgesics: there is limited evidence from controlled trials that both paracetamol and ibuprofen reduce some symptoms of cold such as pain and temperature. However, they have no effect on the specific symptoms of acute bronchitis such as cough. Ibuprofen has more contraindications than paracetamol, but has the advantage of probably being more effective at reducing temperature and requiring less frequent dosing.
• Aspirin and other nonsteroidal anti-inflammatory drugs (other than ibuprofen) are not recommended, as they are more likely to cause serious adverse effects.
• In particular, aspirin should be avoided in older people who are more prone to its adverse effects, or who are taking concomitant nonsteroidal anti-inflammatory drugs or aspirin for cardiovascular purposes.
• Preventing dehydration:
• In clinical practice dehydration is a commonly observed problem for people that are unwell with a chest infection.
• It occurs because they have increased fluid losses from sweating and/or a reduced fluid intake due to general malaise.
• It may not be recognized by someone who is unwell because many of the symptoms of dehydration such as headache, dry mouth, and general malaise may be wrongly attributed to their infective illness rather than dehydration.
• For someone who is unwell dehydration may be most easily recognized by observing urine colour and output, and may be relieved by increasing fluid intake appropriately.
• Cough medicines to suppress a productive cough are not recommended because they suppress the natural mechanism that keeps the airway clear. In principle, suppression of an unproductive cough is unlikely to cause harm [SIGN, 2002]. However:
• Cough medicines that are available over the counter are largely ineffective, and may have associated adverse effects [Morice et al, 2006].
• They may have a useful placebo effect. Because they have little effect at suppressing cough, there is probably no harm in someone continuing to use them even for a productive cough if they have already bought them.
• Opioids in doses higher than recommended in over-the-counter preparations may suppress cough but also have significant adverse effects and are therefore not recommended.
• Smoking cessation is widely advocated because:
• Smoking cessation reduces irritation to the bronchial tree already inflamed due to infection, and theoretically may reduce coughing.
• Smoking is a risk factor for acute bronchitis. Smoking cessation reduces the risk of further episodes of acute bronchitis, in addition to conferring many other health benefits.
• Beta₂-agonists are not routinely recommended for the treatment of acute bronchitis. A Cochrane review (search date: November 2005) found beta₂-agonists only benefited adults with evidence of airway obstruction, and that overall the evidence did not support the use of these drugs in people with acute bronchitis [Smucny et al, 2006].
• Chinese medicinal herbs are not recommended in people with acute bronchitis. A Cochrane review (search date: March 2005) found that although some studies did suggest benefit, these were open to study bias and methodological flaws, and as such overall they cannot be recommended for routine use [Wei et al, 2005].

Basis for not recommending antibiotics for people with acute bronchitis who are otherwise well

• Antibiotics should be reserved for people where there is a risk of serious harm from even a modest deterioration in their chronic condition, or for people who are at risk of a more severe infection because their ability to deal with infection is impaired.
• For people with acute bronchitis who do not have pre-existing pulmonary disease, there is evidence from a Cochrane systematic review that antibiotics have a modest effect in reducing the duration of cough in some individuals.
• Although there is evidence of benefit, the magnitude of this benefit needs to be balanced against the probability of harm from antibiotics for the individual. Some studies have estimated that adverse effects of antibiotics are as frequent as any beneficial effects [SIGN, 2002].
• Current evidence suggests that resistance to the main pathogens implicated in acute bronchitis is not yet widespread in the UK, but increased prescribing of antibiotics is a known mechanism of bacterial resistance, and countries with widespread prescribing of antibiotics in primary care also tend to exhibit greater levels of resistance. Therefore it is prudent not to prescribe antibiotics for self-limiting illnesses whenever possible.
• Based upon considerations of benefit, harms, and increased antibiotic resistance, there is widespread agreement amongst experts that antibiotics are not recommended for people with acute bronchitis who do not have any significant pre-existing conditions.

[Fahey et al, 2004; Braman, 2006]

Basis for considering a delayed prescription strategy for people with acute bronchitis who are otherwise well

• There is evidence that delayed antibiotic prescribing is an effective strategy for managing acute bronchitis. There is no difference in antibiotic consumption between the delayed and no prescribing strategies, and people given delayed prescriptions do not develop diarrhoea significantly more than people offered a no antibiotic prescribing strategy.
• A potential advantage of the delayed prescribing strategy is that it offers a safety net for the small proportion of people with acute bronchitis who develop complications or whose symptoms worsen significantly. A person with acute bronchitis may also prefer to have a delayed prescription rather than no prescription at all, and this could help to maintain the doctor-patient relationship [NICE, 2008].

Basis for considering antibiotics for people with acute bronchitis who are unwell with other conditions

• With the exception of people with COPD, CKS found no direct evidence to support the use of antibiotics for people with acute bronchitis and other conditions.
• Recommendations for when to prescribe an antibiotic in people with a pre-existing condition are therefore based upon:
• Extrapolation from the evidence of the benefit of antibiotics for people who do not have a pre-existing condition, and the assumption that people with pre-existing conditions who are at greater risk of harm from acute bronchitis would gain greater benefit from treatment.
• Evidence of benefit of antibiotics for people with acute bronchitis and COPD. For further information, see the CKS topic on Chronic obstructive pulmonary disease.
• Expert opinion issued in guidelines for the management of adult respiratory tract infections by the European Respiratory Society [Woodhead et al, 2005]. This recommends prescribing antibiotics for people with certain co-existing conditions and people over 75 years of age with fever.
• Additional advice to treat people who are immunocompromised is a pragmatic recommendation from CKS.
• Antibiotics should be reserved for people where:
• There is a risk of serious harm from even a modest deterioration in their chronic condition caused by acute bronchitis.
• They are at risk of a more severe infection because their ability to deal with infection is impaired.

This recommendation is consistent with those of the Health Protection Agency [HPA and Association of Medical Microbiologists, 2008], with the exception that CKS also recommends the use of macrolides in the event that amoxicillin or doxycyline is unsuitable for the person to be treated.

• Empirical treatment is necessary as sputum samples are impractical for identifying a causative pathogen in primary care [SIGN, 2002; British Thoracic Society, 2004].
• There is no evidence from controlled trials to support the use of one antibiotic over another in the treatment of acute bronchitis. Therefore the choice of antibiotic should reflect their in vitro efficacy against the pathogens most likely to be involved, especially Streptococcus pneumoniae and Haemophilus influenzae.
• Amoxicillin provides coverage against most of the bacteria involved in acute bronchitis, including penicillin-intermediate resistant S. pneumoniae (bacteria in an intermediate stage of developing full penicillin resistance), when used at adequate doses [Bush, 2003; British Thoracic Society, 2004]. It has a favourable risk/benefit ratio, with few adverse effects.
• Doxycycline is active against most of the bacteria that cause bronchitis, including H. influenzae and, less commonly encountered, Mycoplasma pneumoniae [Chopra, 2003]. Oxytetracycline is another option, but requires more frequent dosing.
• Clarithromycin is a suitable alternative to amoxicillin in people allergic to penicillin. It is active against most of the bacterial pathogens involved in acute bronchitis [Bryskier and Butzler, 2003], although resistance to them is increasing, especially in H. influenzae.
• Clarithromycin is recommended in preference to erythromycin by the BTS guidelines for the management of community acquired pneumonia, on the basis of improved gastrointestinal tolerance and an easier dosing schedule [British Thoracic Society, 2009].

Basis for advising re-consultation if the person's condition deteriorates

• A significant deterioration may be caused by pneumonia that was not previously clinically apparent.

Basis for management options for people that do not improve, or who worsen, on antibiotics

• Based upon the known pathogens causing acute bronchitis, people that do not improve whilst receiving antibiotics are likely to have one of the following [Macfarlane et al, 2001]:
• An underlying viral infection.
• A streptococcal infection resistant to amoxicillin.
• An atypical bacterial infection not susceptible to any penicillin antibiotics.
• The majority of people who do not improve on antibiotics will have a viral infection and discontinuing the antibiotic will not cause any deterioration in their condition.
• In a minority of people, prescribing a second antibiotic may result in improvement when there is an underlying bacterial cause that was not susceptible to the first-line choice. This may be a reasonable option for people who are seriously ill with a pre-existing condition, when any further deterioration is likely to have serious consequences.
• Co-amoxiclav or doxycycline are suitable second-line antibiotics in people who have previously taken amoxicillin.
• Co-amoxiclav is a combination product containing amoxicillin and clavulanic acid. This is an inhibitor of beta-lactamase, an enzyme that is present in many penicillin-resistant bacteria, and helps amoxicillin retain its efficacy. In particular, co-amoxiclav should be effective against penicillin-resistant strains of Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae.
• Doxycycline has a different spectrum of activity to amoxicillin, and should be considered if previous amoxicillin failure was suspected to be due to Mycoplasma pneumoniae or Chlamydia pneumoniae (although this will not be known for certain in practice).
• If amoxicillin was not previously used due to allergy or other contraindications, it is reasonable to seek advice on second-line treatment from a microbiologist. A macrolide may be suitable, although this may not provide adequate coverage. Fluoroquinolones tend to be effective with few adverse effects, but prescribing these drugs in primary care should be restricted because of fears of growing resistance.

Basis for recommending pneumococcal vaccination

• S. pneumoniae is one of the pathogens known to cause acute bronchitis [Macfarlane et al, 2001].
• The effectiveness of pneumococcal vaccination in preventing morbidity and mortality from S. pneumoniae has been demonstrated in a meta-analysis of 14 randomized controlled trials (n = 48,837) [Cornu et al, 2001].

Basis for recommending influenza vaccine

• The influenza virus is one of the pathogens known to cause acute bronchitis [Macfarlane et al, 2001].
• A number of randomized controlled trials and cohort studies have demonstrated that influenza immunization is effective for:
• Reducing the incidence of influenza.
• Reducing morbidity and mortality from secondary bacterial infections following influenza, particularly in at-risk groups.