• Most adults and older children reliably self-diagnose the common cold within a day of developing symptoms. Diagnosis is made through clinical history.
• Common symptoms include:
• Sore or irritated throat. This is often the first symptom. It typically has a sudden onset and resolves rapidly.
• Nasal irritation, congestion, nasal discharge (rhinorrhoea), and sneezing. Nasal discharge is often profuse and clear at first, but becomes thicker and darker as the infection progresses (although this does not usually indicate that bacterial infection is present).
• Hoarse voice (caused by laryngitis).
• Cough develops in about 30% of colds, typically after nasal symptoms have cleared.
• A general feeling of malaise and being unwell.
• Other symptoms are less common.
• Fever is unusual in adults and, if present, will be low-grade.
• Headache and muscle pain (myalgia) may be present, but these symptoms are more often associated with influenza.
• Loss of taste and smell, a mild burning of the eyes, and a feeling of pressure in the ears or sinuses due to obstruction or mucosal swelling may occur.
• Clinical examination and investigations, (such as nasal and throat swabs) are not necessary to diagnose the common cold.

• Recommendations for the diagnosis of the common cold are based on expert reviews [Gwaltney, 1995; Turner, 1998; Heikkinen and Jarvinen, 2003; Tolan and Nguyen, 2007].

• Ask about the child's symptoms. Parents may report the child as having the following symptoms.
• Restlessness or irritability.
• Fever.
• Nasal congestion with sneezing and nasal discharge. Severe nasal congestion may interfere with feeding, breathing, and sleep.
• Cough. Occasionally, vomiting may follow a bout of coughing.
• Examine younger children and babies, primarily to rule out more serious causes of the reported symptoms.
• Look for sneezing, coughing, or nasal discharge (rhinorrhoea).
• Measure the child's temperature. A fever in the range of 38–39°C is common in preschool children.
• Consider examining:
• The throat. This is not usually inflamed in the common cold, and an inflamed throat in the absence of nasal symptoms is more likely to indicate streptococcal infection.
• Cervical lymph nodes. Mildly enlarged but nontender nodes are consistent with the common cold.
• The ear drum. Look for for signs of acute otitis media.
• Investigations, such as nasal and throat swabs, are not necessary to diagnose the common cold.

• Recommendations for the diagnosis of the common cold are based on expert reviews [Gwaltney, 1995; Turner, 1998; Heikkinen and Jarvinen, 2003; Tolan and Nguyen, 2007].

The symptoms of the common cold can be vague and may overlap with those of other, more severe illnesses. The likelihood of a specific illness being present depends on the age of the person experiencing the symptoms. For illnesses that may follow on from the common cold, see Complications.

• Influenza ranges from asymptomatic carriage to severe, life-threatening infection. Milder symptoms of influenza are frequently misdiagnosed as the common cold. If symptoms of muscular pain (myalgia) or fever are prominent, suspect influenza. See the CKS topic on Influenza - seasonal.
• Streptococcal pharyngitis may cause a sore throat that is mistaken as the common cold. Usually pain is more severe if infection with Streptococcus pyogenes is responsible, and cough, sneeze, and nasal congestion are absent. See the CKS topic on Sore throat - acute.
• Allergic rhinitis can present with nasal symptoms similar to those of the common cold. See the CKS topic on Allergic rhinitis.
• Infectious mononucleosis (glandular fever) is prevalent in young adults and adolescents. It is a chronic infection characterized by prolonged fever, a severe sore throat, fatigue, and swollen lymph nodes.
• Meningitis. Signs and symptoms that make a diagnosis of meningitis more likely include:
• Purpuric rash that does not fade when a glass is pressed against it.
• In infants and babies — a high fever; loss of consciousness; blank, staring expression; vomiting and loss of appetite; high-pitched screaming or whimpering; floppiness, with a dislike of being held; and/or a tense or bulging fontanelle.
• In older children and adults — fever, vomiting, stiff neck, photophobia, severe headache, muscular pains, fits, stomach cramps (caused by septicaemia), and/or confusion.
• Pertussis (whooping cough) may cause prodromal symptoms similar to those of the common cold, but it should be easily diagnosed once the characteristic cough develops.
• A foreign body should be considered if a child has a persistent, unilateral nasal discharge in the absence of other symptoms.

The differential diagnosis of the common cold is described in guidelines published by the Institute for Clinical Systems Improvement [ICSI, 2004] and an expert review [Heikkinen and Jarvinen, 2003].