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A woman developed cough symptoms after a cold, and she took amoxicillin and compound licorice mixture for 3 days, but it had no effect. Going to the hospital for chest X-ray examination was normal. The doctor thought she was suffering from a cough after a cold. She was treated with azithromycin, chlorpheniramine and dextromethorphan. After one week of treatment, the symptoms of cough disappeared.


I. What is a cough after a cold?

When the acute phase of respiratory infection disappears, the cough is still prolonged and healed. It is usually characterized by irritating dry cough or coughing a small amount of white mucus, usually lasting for 3 to 8 weeks. There is no abnormality in X-ray examination. It is called cough after infection. (PIC). Among them, cough caused by a viral cold is the most common, also known as “cough after a cold.”

The pathophysiological mechanism of cough after a cold is not yet clear. It is currently believed to be caused by viral infection with or without transient airway hyperresponsiveness. Studies have found that reversible airway hyperresponsiveness induced by respiratory virus infection takes up to 7 weeks to return to normal levels.

Because of the high reactivity of the airway after a cold, if you encounter external stimuli or cold air, it can cause coughing. When you go out, you should wear a mask. At the same time, pay attention to the cleanness of the indoor environment and avoid exogenous stimuli such as pollen, animal skin and oily smoke.


II. What medicine can I use for cough after a cold?

Cough after a cold is a self-limiting disease that usually resolves over time. There is currently no specific treatment. For patients with obvious cough symptoms, it is recommended to use antitussives, antihistamines, decongestants, etc. for short-term use.

1. Dextromethorphan

Dextromethorphan is a central antitussive drug commonly used in clinical practice. It is mainly used to treat dry cough caused by cold, pharyngitis and bronchitis. At the therapeutic dose, dextromethorphan was not addictive and had no respiratory depression.

Special reminder: women, lactating women, and people with a history of mental illness are prohibited within 3 months of pregnancy, and they are not allowed to drive vehicles and operate machines during medication.

2. Antihistamines

Antihistamines are preferred first-generation H1 receptor antagonists, such as chlorpheniramine, ketotifen, and the like. Among them, the antihistamine effect of ketotifen is 10 times stronger than that of chlorpheniramine and long-acting.

In addition to its antihistamine effect, ketotifen can relax smooth muscle and have the activity of stabilizing mast cells similar to sodium cromoglycate. It can be used for the prevention of asthma, but it takes several weeks to exert the best effect. For the treatment of acute asthma attacks.

Special reminder: The main adverse reaction of the first generation of antihistamines is lethargy. It is not advisable to drive the vehicle or operate the machine during the medication. It should also avoid drinking alcohol. Children under 2 years old should also be used with caution. Ketotifen can cause weight gain.


III. Under what circumstances can azithromycin be used?

Respiratory viruses associated with colds include rhinovirus, coronavirus, influenza virus, parainfluenza virus, respiratory syncytial virus, and the like. Therefore, coughing after a cold does not require the simultaneous application of antibacterial drugs.

However, coughing after infection caused by atypical pathogens such as mycoplasma and chlamydia may cause pathogens to persist in the body for a prolonged period of time, which may cause prolonged cough. In the treatment of cough-related symptoms in such patients, macrolide antibiotics such as azithromycin should be used as soon as possible.

In addition, studies have shown that the use of low-dose azithromycin in patients with stable chronic obstructive pulmonary disease can effectively reduce airway inflammation, inhibit mucus hypersecretion in lung tissue, improve lung function, and prevent repeated disease.


IV. After coughing for a cold, don’t you need montelukast?

In patients with cough after infection, the level of leukotrienes is increased, and leukotrienes are associated with cough sensitivity, suggesting that leukotriene receptor antagonists may be effective in treating cough after infection.

However, a recent randomized, double-blind, placebo-controlled clinical study showed that 137 patients with post-infectious cough who received leukotriene receptor antagonist montelukast had post-infection cough symptoms, cough-related quality of life, and placebo There is no significant difference.

Therefore, montelukast is not effective in treating cough after infection and is not recommended. In addition, inhaled corticosteroids (ICS) are not recommended for cough after a cold and are not recommended.

Special reminder: If the duration of cough is more than 8 weeks, you should pay attention to the possibility of other causes. It is recommended to further check the diagnosis.

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