The use of symptomatic treatments other than simple analgesia is not recommended by most guideline groups or expert reviewers [ICSI, 2004; MeReC, 2006]. In general, the benefits of other treatments are outweighed by their potential to harm or by other considerations. For detailed information on the available evidence from randomized controlled trials (RCTs) for these treatments, see Supporting evidence.

• Antibiotics would not be expected to be effective for the treatment of the common cold, which is caused by viral rather than bacterial infection:
• This ineffectiveness was confirmed by a systematic review [Arroll and Kenealy, 2005].
• In addition to being ineffective, antibiotics may cause adverse effects. One review found that for every 16 people treated, one would have an adverse effect (NNH = 16) [Arroll, 2006].
• Antihistamines used alone have been shown to be ineffective by a systematic review [De Sutter et al, 2003]. Sedating antihistamines may reduce some symptoms when combined with a decongestant (probably because they have anticholinergic effects), but the risk of adverse effects (e.g. drowsiness) outweighs any benefit of this approach. Non-sedating antihistamines are completely ineffective.
• Vitamin C and zinc are the most commonly recommended vitamins and minerals. However, the available evidence for vitamin C suggests that it has an effect only when taken at large doses as prophylactic treatment, and the benefit is likely to be small [Douglas et al, 2004]. The evidence for the use of zinc is even less convincing [Marshall, 2006].
• Complementary and alternative therapies are increasingly popular treatments for colds, but there is little evidence to support their use in the treatment or prevention of the common cold.
• Echinacea has shown some benefit in RCTs, but the optimum formulation is unknown and quality control remains a problem [Linde et al, 2006].
• Chinese herbal medicines have not been shown to be effective by high-quality controlled trials [Wu et al, 2007].
• Over-the-counter cough and cold products containing certain ingredients should no longer be used in children under 6 years, because the balance of benefits and risks has not been shown to be favourable [MHRA, 2009].
• A Medicines and Healthcare products Regulatory Agency (MHRA) review examined the safety and efficacy of children's cough and cold medicines, and found there is no good evidence that they work. There have been some reports of harm, for example, rarely they can cause side effects such as allergic reactions, effects on sleep, and hallucinations [MHRA, 2009].
• For children over 6 years of age, it is felt that these risks are reduced, as with increased age and size, these medicines are tolerated better [MHRA, 2009].
• In addition, there is no convincing evidence from RCTs that cough medicines make a clinically significant difference to cough or other cold symptoms, but they may have a useful placebo effect [Schroeder and Fahey, 2004].
• Decongestants are available as topical or oral preparations. Evidence from a systematic review indicates that decongestants relieve nasal congestion in the short term, but this effect does not extend past a few days, and the benefit is relatively small [Taverner and Latte, 2007].