Although the common cold is caused by viral infection, due to the sheer volume of potential common cold viruses and treatment timing, targeted anti-viral drugs are not typically beneficial (Pappas 2009). In addition, antibacterial drugs (i.e., antibiotics) are of no benefit in the treatment of the common cold (Turner 2009), except for in severe cases involving complication such as secondary bacterial sinusitis (Nussenbaum 2010). In fact, the use of antibacterial medications for treating uncomplicated colds is likely to do more harm than good, as they can induce adverse reactions as well as contribute to the development of drug resistant pathogens (CDC 2012b).
Over-the-Counter Cold Medicines Nearly $3 billion worth of OTC cold medicines are purchased each year, but randomized trial evidence suggests minimal effectiveness (Turner 2009; De Sutter 2009; Barrett 2007).
The following list comprises commonly used over-the-counter cough and cold medications along with their specific indications (Turner 2009; Simasek 2007; Dealleaume 2009):
Oxymetazoline and pseudoephedrine – These drugs are alpha-adrenergic agents. When use topically or orally, these agents may help relieve stuffy nose symptoms by causing blood vessels to constrict (Atkins 2011). Decongestants like pseudoephedrine can increase blood pressure and should not be used by people with hypertension (Simasek 2007).
Diphenhydramine – Diphenhydramine blocks the effects of histamine in the body, which is a proinflammatory component of the immune system. It may be beneficial for treating runny nose, sneezing, coughing, and nausea (Turner 2009; Clinical Pharmacology 2012a; MD Consult 2012a). Diphenhydramine also causes sedation and may cause arrhythmia and/or tachycardia and so should be used with caution by people who have heart problems (Simasek 2007).
Dextromethorphan – Dextromethorphan is a cough suppressant drug. It appears to reduce coughing via several actions within the brain (Clinical Pharmacology 2012b; MD Consult 2012b). Potential side effects of dextromethorphan include confusion, excitability, gastrointestinal disturbances, irritability, nervousness, and sedation (Simasek 2007).
Mild Analgesics - Acetaminophen and non-steroidal anti-inflammatory drugs (NSAIDs) (e.g., aspirin, ibuprofen, and naproxen) are drugs that provide analgesic, fever-reducing, and anti-inflammatory effects. These drugs may help alleviate painful symptoms such as a sore throat or muscle pain associated with the common cold (Turner 2009). It is important to consider that acetaminophen is an ingredient in many OTC cold medicines and can be toxic if consumed in excess. Therefore, it is imperative to read the labels of cold medicines carefully to avoid excess consumption of acetaminophen. Life Extension suggests that at least 600 mg of N-acetyl cysteine be taken with each dose of acetaminophen to help the liver detoxify harmful metabolic derivatives of the drug. More information is available in the Acetaminophen and NSAID Toxicity protocol.People taking combination cough and cold medicines should be conscious of all the ingredients and doses contained within (e.g., some products contain up to 5 distinct ingredients), and make sure that they are not duplicating therapy or taking more than is recommended (Mayo Clinic 2012; Erebara 2008). Given that over-the-counter drugs have not been demonstrated to be beneficial for the treatment of cold in young children and their potential for toxicity, these medications are not recommended for children under 4 (Turner 2009).
Protecting Against the Common Cold with a Stomach Acid Medication Cimetidine is an over-the-counter drug that blocks certain histamine receptors (i.e., histamine receptor type 2 antagonist); it is approved by the FDA for inhibition of gastric acid secretion. In addition to its usefulness for treating gastric or duodenal ulcers (Scheinfeld 2003; Kubecova 2011), cimetidine has also been shown to augment immune response against viral pathogens (Shin 2012; Arae 2011; Wang 2008; Zhang 2011; Wang 2008; Stefani 2009).
One of cimetidine's important actions is inhibition of suppressor T-cells, which are cells of the immune system that normally "turn down" the immune response (Wang 2008; Li 2011). In other words, taking cimetidine at the first sign of a cold may allow for a more robust immune response by countering the effects of these intrinsic immune regulators.
New Drug Significantly Reduces Cold Symptoms in Clinical Trial
Results of a phase II clinical trial show that a new antiviral, vapendavir, reduced symptoms of rhinovirus infection among people with asthma (EvaluatePharma 2012).
Vapendavir works by blocking entry of viruses into host cells, thereby preventing infection.
Compared to those who took a placebo, vapendavir recipients experienced significantly less cold symptoms during days 2 and 4 of infection, when symptoms are typically worst. Moreover, those who took the new drug experienced earlier improvement of symptoms compared to those who took a placebo (1.7 days vs. 2.5 days).
More trials are needed before vapendavir becomes widely available as a common cold treatment, but these early results are encouraging.