Symptoms of whooping cough typically last 6 to 10 weeks (but may last longer). In young children, three stages can occur. Older children and adults don't always go through the same stages.

First stage

Coldlike symptoms begin and last for several days to 2 weeks. Symptoms usually include sneezing, a runny nose, mild coughing, watery eyes, and sometimes a mild fever. An infected person is most contagious during this stage.

Second stage

The most serious symptoms develop during this phase and last about 2 to 4 weeks or longer. As coldlike symptoms fade, the cough gets worse. A dry, hacking cough turns into bursts of uncontrollable, often violent coughing that may make it temporarily impossible to breathe. This may happen up to 30 times a day. The person may quickly inhale when trying to take a breath through airways narrowed by inflammation, which sometimes creates a whooping noise.

In babies, coughing spells:

• May be triggered by very slight stimulation, such as taking in food or milk, sucking, exposure to a sudden sound or light, or stretching.
• May cause symptoms of flushed cheeks, pale or bluish complexion from lack of oxygen, and bulging or watery eyes. A baby may also stick out his or her tongue, push the chest forward, or flail arms and legs in distress.
• May be frightening to watch, although most babies recover and regain control of their breathing on their own. Babies generally feel well between coughing spells but may become exhausted from the physical effort of coughing. It's also possible that your baby's breathing could stop for a short time during the coughing spells. This is called apnea.
• May lead to hospitalization, especially if the baby is younger than 4 months of age. Hospitalization allows health professionals to monitor the baby's condition and evaluate how well he or she tolerates and recovers from coughing episodes.

Third stage

The final stage, lasting for a few weeks or months, is a gradual recovery period. Although the person gains strength and begins to feel better, the cough may become louder and sound worse. Coughing spells become less frequent but may flare up again if a cold or other upper respiratory illness develops. This final stage may last longer in people who were not given the whooping cough (pertussis) vaccine.

Complications, such as pneumonia or exertion-related injuries from coughing, such as a hernia, can develop from whooping cough. These types of health problems pose the most serious risk to children younger than 4 months and adults ages 60 and older.