context: If you have asthma, catching a cold may worsen or trigger your symptoms. It's important to understand asthma symptoms and cold symptoms and to know which asthma medicines you need to use to prevent asthma flares and asthma attacks. The information here about asthma can help you stay well when coping with asthma and a cold. Asthma is associated with inflammation of the lower airways inside your lungs called the bronchial tubes. Colds result from infection with a virus. Cold viruses mainly affect your nose and throat. These are the upper airways. You normally take air into your body through your nose and windpipe into your bronchial tubes, which go on to branch into smaller tubes. At the end of these tubes there are tiny air sacs called alveoli that deliver oxygen and remove carbon dioxide from the blood as we breathe. During normal breathing, the bands of muscle that surround the airways are relaxed. Air moves freely. During an asthma attack, three main changes occur that stop air from moving easily through the airways: The bands of muscle that surround the airways tighten. This makes the airways narrow. This tightening is called bronchospasm. The lining of the airways becomes swollen or inflamed. The cells that line the airways produce more mucus, which is thicker than normal. All of these factors -- bronchospasm, inflammation, and mucus production -- cause asthma symptoms such as difficulty breathing, wheezing, coughing, breathlessness, and difficulty performing activities. Colds are respiratory infections caused by viruses. Several hundred different viruses may cause your cold symptoms. These viruses can also affect your airways, sinuses, throat, voice box, and bronchial tubes. Not every person with asthma has the same symptoms in the same way. Symptoms of asthma may also vary from one asthma episode to the next. They might be mild one time and severe another time. Asthma does not cause a fever, chills, muscle aches, or sore throat. The most common asthma symptoms include: Frequent coughing Shortness of breath Wheezing Chest tightness Cold symptoms often begin with throat discomfort or sore throat. That discomfort is followed by clear, watery nasal discharge; sneezing; fatigue; and sometimes a slight fever. Postnasal drip from your nose and sinuses can causes you to have acough. For the first few days of a cold, your nose is filled with watery nasal secretions. These secretions may become thicker and darker. Dark mucus does not necessarily mean that you have developed a bacterial infection. Call your doctor if you experience any of these signs: Fever (with a temperature over 101 ° F) or chills Increased fatigue or weakness A very sore throat or pain when swallowing Sinus headaches, upper toothaches, or tenderness or pain of the upper cheekbones Coughing up greater amounts of yellow- or green-colored mucus Difficulty swallowing your saliva Also call your doctor if you have any other symptoms that cause concern, such as the following: Increased shortness of breath, difficulty breathing, or wheezing Symptoms getting worse or remaining unchanged after seven days Symptoms remaining unchanged or getting worse after 10 days Eye pain or swelling and/or vision changes Severe head or facial pain or swelling Neck stiffness or sensitivity to light Good hygiene can decrease viral infections such as colds. Prevent the spread of cold viruses by making sure you and your family members wash your hands regularly. Another way to protect yourself is to get a flu vaccine every year. Like colds, the flu is caused by a virus and can trigger asthma problems. Ask your doctor for a written asthma action plan during your next visit. This plan may suggest that you increase the dosage or frequency of the medications that you already take when a cold causes your asthma to worsen. It may also include adding a prevention inhaler (like a steroid inhaler) when you get a cold even if you aren't having asthma symptoms yet. Your plan will specify when symptoms warrant a call to your doctor. In addition, you should eliminateor avoid environmental factors that may be contributing to the asthma attack such as smoke, allergens, cold air, or chemicals.