Early symptoms can last for 1 to 2 weeks and usually include:
Runny or stuffed-up nose
Low-grade fever (less than 100.4°F)
Mild, occasional cough (babies do not do this)
Apnea (life-threatening pauses in breathing) and cyanosis (turning blue or purple) in babies and young children
In its early stages, whooping cough appears to be nothing more than the common cold. Therefore, doctors often do not suspect or diagnose it until the more severe symptoms appear.
Stage 2
One to 2 weeks after the first symptoms start, people with whooping cough may develop paroxysms—rapid, violent, and uncontrolled coughing fits. These coughing fits usually last 1 to 6 weeks but can last for up to 10 weeks. Coughing fits generally get worse and become more common as the illness continues.
Coughing fits can cause people to
Make a high-pitched “whoop” sound when they are finally able to inhale at the end of a coughing fit
Vomit during or after coughing fits
Feel very tired after the fit, but usually seem well in-between fits
Struggle to breathe
Babies may struggle to breathe, while teens and adults usually have mild symptoms
Many babies with whooping cough don’t cough at all. Instead it may cause them to turn blue or struggle to breathe. It may seem like a common cold for the entire illness, not just the beginning.
The infection is generally milder in teens and adults than in babies and children, especially those who have gotten vaccinated against whooping cough. It may seem like a common cold. The “whoop” is often not there for people who have a milder illness.
However, teens and adults can have serious cases of whooping cough. Teens and adults, especially those who did not get whooping cough vaccines, may have lengthy coughing fits that keep them up at night. Those who get these coughing fits say it’s the worst cough of their lives. It can also cause major disruptions to daily life and serious complications.
https://www.cdc.gov/pertussis/about/signs-symptoms.html