The symptoms of whooping cough usually appear around a week after infection with the bacteria Bordetella pertussis. But this delay – known as the incubation period – can last up to 21 days.

Whooping cough tends to develop in stages, with mild symptoms occurring first, followed by a period of more severe symptoms, before improvement begins.

Early symptoms

The early symptoms of whooping cough are often similar to those of a common cold and may include:

• dry, irritating cough
• runny or blocked nose
• sneezing
• watering eye
• sore throat
• slightly raised temperature
• feeling generally unwell

These early symptoms of whooping cough can last up to a week, before becoming more severe.

Paroxysmal symptoms

The second stage of whooping cough is often called the paroxysmal stage and is characterised by intense bouts of coughing. The bouts are sometimes referred to as "paroxysms" of coughing.

The paroxysmal symptoms of whooping cough may include:

• intense bouts of coughing, which bring up thick phlegm
• a "whoop" sound with each sharp intake of breath after coughing (although this may not occur in infants and young children, see below)
• vomiting after coughing, especially in infants and young children
• tiredness and redness in the face from the effort of coughing

Each bout of coughing usually lasts between one and two minutes, but several bouts may occur in quick succession and last several minutes. The number of coughing bouts experienced each day varies, but is usually between 12 and 15.

The paroxysmal symptoms of whooping cough can last a month or more, even after treatment. This is because the cough continues even after the Bordetella pertussis bacterium has been cleared from your body.

Infants and young children

Infants younger than six months may not make the "whoop" sound after coughing, but they may start gagging or gasping, and may temporarily stop breathing.

Though very rare, it is possible for whooping cough to cause sudden unexpected death in infants (see complications of whooping cough for more information).

Young children may also seem to choke or become blue in the face (cyanosis) when they have a bout of coughing. This looks worse than it is, and breathing will quickly start again.

Adults and older children

In adults and older children, the paroxysmal symptoms of whooping cough are usually less severe than in young children, although the cough may still last for several weeks.

Recovery stage

Eventually, the symptoms of whooping cough gradually start to improve, with fewer and less extreme bouts of coughing occurring. This period of recovery can last up to two months or more.

However, intense bouts of coughing may still occur during this period.

When to seek medical advice

You should always see your GP if you think you or your child may have developed whooping cough.

If this is the case you will need to be prescribed antibiotics.

When to seek immediate medical advice

You should seek immediate medical advice if:

• you have a baby of six months or younger who appears to be very unwell – read more about spotting the signs of serious illness in young children
• you (or your child) appear to be experiencing significant breathing difficulties such as extended periods of breathlessness
• you (or your child) develop serious complications, such as seizures (fits) or pneumonia, an infection that causes inflammation of the tissues in your lungs

Call your GP immediately. If this is not possible then call NHS 111 or your local out-of-hours service.