Secondary drowning.

  This week, a U.S. mom shared her scary story of her son's near-drowning as a cautionary tale to other families. It wasn't her toddler's initial scare that she's warning about - it's the secondary drowning that followed.

San Diego mommy blogger Lindsay Kujawa said that her son was underwater for about 20 seconds while at a pool party.

What is secondary drowning?

After a near-drowning incident, parents may be relieved to get their child back to safety, but there's a possibility that kids can drown once they're out of the water, according to experts.

"It's something a lot of people don't realize. When one thinks of drowning, you think of it happening right away. This is where near-drowning becomes a risk," Shauna Moulton, a Red Cross swimming and water safety representative, told Global News.

The Cleveland Clinic points to two phenomena: dry drowning and secondary drowning. They can occur after a child struggles in the water and is saved. They can both lead to brain injury, respiratory problems or even death, the medical authority warns on its website.

While drowning, a swimmer may breathe water into their lungs. In dry drowning, the larynx shuts as a defense - no water is getting in, but no air is getting in either.

In secondary drowning, water is aspirated into the lungs and collects there. The water collected in the lungs makes it difficult to breathe, and victims often make a "crackle" sound as they try to.

"This is why every child who has fallen into the water or experienced a near-drowning should be taken to the emergency room immediately," pediatrician Dr. Elumalai Appachi says.

"If we can intervene quickly, it's possible for a child to recover," he said.

A review on secondary drowning suggested that about five per cent of kids who have drowning scares go on to encounter secondary drowning. Sometimes, kids recover fully. But on the other end of the spectrum, there are fatalities.

Luckily, in Kujawa's case, her son survived. He was sent to the ER for chest X-rays and a list of blood tests, in which doctors learned he had chemical pneumonitis from the water in the pool.

He was rushed to a children's hospital and treated. 

"I want to make sure this never happens to another child so pass this on and please share with those who you think might need to know," Kuwaja writes.

What are the signs of secondary drowning?

Moulton says there are a string of warning signs that your child may be dealing with secondary drowning.

But a general rule of thumb: watch your child for the next 24 hours to look for signs such as shortness of breath, differences in breathing, such as heavy or shallow breaths, abnormal skin colour, such as looking pale or clammy, and shivering.

Also, look out for:  

• Irritation or pain in the throat or chest
• Coughing after taking a deep breath
• Persistent coughing or wheezing
• Shortness of breath or difficulty breathing
• Unusual fatigue
• Dizziness/altered level of consciousness
• High fever