Lindsay Kujawa was sitting inches from her toddler son, Ronin, as he played on the top step of the hot tub. She turned away for five seconds and when she turned back he was floating. “His little head was bobbing up and down trying desperately to get air,” she says. When she pulled him out, he sputtered and coughed, but he soon seemed back to normal.

Hours later, however, Ronin was acting strange. In a blog about the incident, Kujawa recalls that he seemed exhausted and was coughing repeatedly.

It could have just been due to the excitement of the day, but she called the doctor just the same. And it’s a good thing she did: After listening to the story, the doctor told Kujawa to rush Ronin to the emergency room. It turns out the toddler was having a massive and potentially fatal inflammatory reaction to the water he had inhaled. He couldn’t get enough oxygen. He was still “drowning,” even though he was nowhere near water.

Fortunately, doctors were able to treat Ronin and he is a happy and healthy boy today. But in the unlikely event that your child ever needs a water rescue, be aware of the warning signs of later trouble.

Related: Silent Drowning: How To Spot The Signs and Save a Life

The danger formerly known as “dry drowning”

Many online stories refer to deaths that occur hours after a water rescue — often when the victim walks away seemingly unharmed — as “dry drowning” or “secondary drowning.” But drowning experts object to these terms, calling them outdated and inaccurate. “Drowning,” in fact, is now defined as suffering respiratory problems that kept someone from breathing air after they were submerged or immersed in water (or another liquid).

The term “secondary drowning,” sometimes used to describe incidents such as Ronin’s, is especially confusing, say experts, because there isn’t necessarily a “primary” drowning. Simply inhaling water may be enough to trigger a medical emergency.

“Those of us in the drowning research community have been very upset by the numerous stories on ‘secondary drowning’ over the past year," said Andrew Schmidt, DO, MPH, an assistant professor at the University of Florida and the director of Lifeguards Without Borders. “It is setting us all back a decade.”

Few parents are aware that their child could be in danger hours after he leaves the pool or ocean. If a child or adult inhales water (whether because they’re having trouble staying afloat or simply because they’re roughhousing), the water can trigger an inflammatory reaction in the lungs hours later.

This reaction can cause severe oxygen depletion, which, if left untreated, can lead to injury and death. Children are more likely to inhale water and so are at greatest risk, according to Kathleen Berchelmann, MD, a pediatrician at St. Louis Children's Hospital who has treated children who appeared normal after a drowning incident but came close to dying several hours later.

Warning signs to watch for

Any child pulled from a pool, lake or ocean should receive medical attention, Berchelmann says. “Obviously if the child is in a lot of distress you should go right to the emergency room, but if he seems stable and you’re not sure, call your pediatrician.”

If your child choked on some water or needed to be rescued, keep a close eye on her for the next 24 hours. One study estimated that about 5 percent of people who survive drowning accidents can expect delayed lung distress within four hours of being rescued. If there is a problem, it usually shows up within 8 hours.

Related: Inflatable Pools: Smaller Doesn’t Mean Safer

Even if your child seems OK and has seen a doctor, watch for these warnings signs of trouble:

Coughing or trouble breathing. “Look for any persistent coughing that lasts for more than one or two minutes,” advises Berchelmann. Coughing means there’s a risk that water is in the lungs.

Foam coming from the mouth or nose. If your child was submerged and inhaled water, foam at the mouth or a frothy pink discharge from the nose and mouth is almost always a sign of a serious and potentially life-threatening lung problem. Call 911 or take your child to the emergency room immediately.

Vomiting. Nausea and vomiting after a day at the pool might mean your child has contracted a water-borne illness. But it could also be a sign of life-threatening injury from drowning, so get immediate care even if it’s unclear whether he inhaled water.

Unusual tiredness, confusion or changes in behavior. These are also reasons to call your doctor immediately and prepare for a possible trip to the ER.

“Often kids seem fine at first, but they can become much worse later on, so it is important that they are monitored overnight in a place that has the necessary medical treatment facilities,” says Berchelmann.

The hospital will focus on making sure your child has enough oxygen and checking for fluid in the lungs. This will likely involve some blood tests and a chest x-ray. Doctors may use drugs to keep your child’s blood pressure stable, an oxygen mask or, in more severe cases, a ventilator.

Patients who are alert or who show only a mild mental dullness in the emergency department "have an excellent chance of recovery," said Joyce Arpilleda, MD, FAAP, a clinical professor of pediatrics at the University of California at San Diego. Children or adults sent home from the ED should return immediately if they develop shortness of breath, cough or fever, she added.

Experts also advise getting CPR training in case you need to revive a drowning victim, and discouraging roughhousing in the water.

“Dunking and holding kids under water should be clearly prohibited by parents and lifeguards,” says Berchelmann.

By knowing the warning signs of trouble after a person is rescued or swallows water, you may save your child — or someone else’s — from a preventable tragedy.

Related: Life-Saving Water Tips: How To Make Your Pool A Drowning-Free Zone

Mary Purcell is a freelance writer and health researcher in Piedmont, Calif., with expertise in policy analysis. She has a master's degree in Latin American studies from Georgetown University.