The practical advice given in this section is consistent with that of the Institute for Clinical Systems Improvement, which is mainly based on expert consensus and extrapolation from the known mechanisms of transmission of viruses implicated in the cold (for details, see Transmission) [ICSI, 2004].

• Explaining that the incidence of the common cold is very high and infection at some stage is unavoidable may help to allay the person's fears.
• A major route of transmission of viruses involved in the common cold is direct bodily contact. Hand washing is thought to reduce transmission of the common cold [Turner and Hendley, 2005], but definitive evidence of clinical benefit from controlled trials is still lacking. Recently, trials have investigated the role of specialised hand washes in preventing the cold.
• A randomized controlled trial (RCT) found that a hand wash containing organic acids reduced transmission of rhinovirus but had no effect on the proportion of people who developed the common cold caused by rhinovirus [Turner et al, 2004].
• A RCT investigating an alcohol-based hand wash found that it reduced transmission of gastrointestinal viral infections but not respiratory infections [Sandora et al, 2005].
• A prospective cohort study found that the use of alcohol washes was associated with a lower transmission rate of respiratory illnesses [Lee et al, 2005].
• The incidence of the common cold in children has been shown to be related to their exposure to day-care facilities and the use of bottle-feeding [ICSI, 2004]. These are also thought to be risk factors in some complications of the common cold, such as acute otitis media. However, no recommendations can be made with regard to these risks, as usually they cannot practically be avoided.
• There is no evidence that vitamin or mineral supplements are effective in preventing the common cold.
• There is no evidence that travel by aeroplane increases the risk of developing the common cold [Mangili and Gendreau, 2005].