14 Common Symptoms of Croup in Kids and Adults

2. Fever

Fever often appears in the early stages of croup. A child may begin with cold-like signs such as a runny nose and mild cough, followed by a rise in body temperature within a few days. The virus that inflames the voice box and windpipe triggers the body’s immune response, which causes both airway irritation and an increase in temperature.

In most cases, the fever is low grade and stays below 101.5°F (38.5°C). Fever can fluctuate throughout the day and may temporarily rise after activity or crying. Even a mild increase in temperature can make a child feel tired, fussy, or less active than usual. Checking the child’s temperature can help caregivers follow the illness and spot any unusual fever changes.

Adults with the same virus may also have a fever, but they often have less airway swelling. In adults, the illness may feel more like a bad cold with a sore throat and a hoarse voice.

3. Hoarseness

Hoarseness is a common symptom of croup, which causes swelling in the voice box and windpipe. As the voice box becomes inflamed, the vocal cords cannot vibrate normally, producing a hoarse or croaky sound when the child talks or cries. The degree of hoarseness can vary throughout the day, often worsening at night or with activity.

It may also improve temporarily after rest or when the child is calm. Hoarseness is usually more noticeable when the child is excited or crying, which can make airway swelling more apparent. In some cases, hoarseness may be accompanied by a weak or muffled cry in younger children due to their smaller airways. Hoarseness can sometimes persist for several days after other cold-like symptoms have resolved as the airway gradually returns to normal.

This symptom often appears after a few days of cold-like signs such as a runny nose, mild fever, or cough. As upper airway swelling increases, the voice may sound rough, weak, or strained, and some children may only be able to speak in a whisper.

4. Labored Breathing

Labored breathing is a serious symptom of croup. It develops when swelling in the voice box and windpipe narrows the airway, reducing airflow and forcing the child or adult to work harder to breathe. As the airway becomes more restricted, breathing may become faster and more effortful, and a high-pitched sound when breathing in often occurs.

The effort to breathe can cause fatigue and restlessness, making it harder for the child to sleep or remain calm. The chest or belly may pull inward with each breath, especially under the ribs or at the base of the neck. Some children may also grunt, flare their nostrils, or show visible strain in the chest muscles. Infants may have difficulty feeding because breathing becomes harder to coordinate with sucking and swallowing.

Symptoms often worsen at night as airway swelling increases, and crying or distress can further raise breathing effort. Adults with croup may experience chest tightness and shortness of breath, although severe airway swelling is less common than in children.

5. Fatigue

Fatigue often develops as the body fights the viral infection that causes croup. The immune system works to control airway inflammation, and this effort can leave a child feeling tired and weak. Fever and other cold-like symptoms, such as a runny nose, can add to exhaustion because the body uses more energy when temperature rises.

Dehydration from fever or reduced fluid intake can also contribute to feelings of fatigue. Reduced oxygen intake from airway swelling may further increase tiredness in some children. Emotional stress from feeling unwell can also intensify fatigue, making children more prone to irritability or tearfulness.

Tiredness often increases after several nights of poor sleep. Croup symptoms, including a barking cough and noisy breathing, tend to worsen at night, leading to frequent waking and disrupted rest. Young children may seem less active, play less, or want to be held more often. Some may also become clingy or irritable due to feeling worn out.

6. Congestion

Congestion often appears in the early stages of croup. The illness usually begins like a cold, so a child may develop a runny or stuffy nose before the barking cough starts. The virus irritates the lining of the nose and upper airway, prompting the body to produce extra mucus. Environmental factors, such as dry air or exposure to smoke, can worsen nasal congestion.

Using a humidifier or sitting in a steamy bathroom may help ease nasal blockage and make breathing more comfortable. This buildup can narrow or block the nasal passages and make breathing through the nose more difficult. Although congestion does not cause the barking cough, it adds to overall airway irritation and discomfort.

In young children, nasal congestion can interfere with feeding and sleep. They may pause often to breathe while eating or become more restless at night. Adults with croup may also have congestion, though it is typically milder.

7. Drooling

Drooling can occur in some children with croup when throat swelling makes swallowing difficult. As irritation increases, swallowing may become painful, causing the child to avoid it. Saliva then collects in the mouth and spills out. The amount of drooling can vary depending on how swollen or irritated the throat is.

Parents may also notice increased throat clearing or gagging as the child tries to manage excess saliva. Drooling may be more noticeable when the child is tired, crying, or lying flat. Some children sit upright or lean forward to manage saliva more easily, as this position can help with both swallowing and breathing. Drooling is seen more often in infants and toddlers because they cannot explain that swallowing is painful.

Although drooling is not common in mild croup, it can signal more significant throat swelling and should be monitored closely. If it appears along with severe breathing difficulty, stridor at rest, or signs of distress, urgent medical evaluation may be needed.

8. Phlegm

Phlegm often builds up in the airways during croup. The infection causes swelling in the voice box and windpipe, which leads the body to produce extra mucus to trap germs and protect the airway lining. This usually begins after a few days of cold-like symptoms such as a runny nose, mild fever, and cough. The color and thickness of the phlegm can vary depending on hydration and the stage of the infection.

Children may cough more forcefully as the body tries to clear the mucus from the airways. As it thickens, the cough may sound wet or rattling. Younger children may have more trouble clearing phlegm because their cough reflex and airway muscles are still developing.

Drinking fluids can help thin the mucus, making it easier to clear. Warm liquids or humid air may also help loosen phlegm and soothe irritated airways. Phlegm can also collect in the back of the throat, which may add to discomfort or trigger gagging.

9. Insomnia

Insomnia can develop when croup symptoms worsen at night. Symptoms tend to flare after bedtime. Lying flat can increase airway irritation, and normal body changes during sleep may make breathing sounds louder and coughing more frequent.

Using a slightly elevated head position or gentle humidified air can sometimes ease nighttime breathing and reduce sleep disruption. Creating a calm bedtime environment, such as dim lighting and minimal noise, may also help children settle despite discomfort. Caregivers may also notice that comforting routines, like gentle rocking or holding, can briefly ease symptoms and help the child return to sleep. Sleep disruption may also increase irritability and clinginess the following day.

Barking cough, noisy breathing, and throat swelling often disrupt sleep, causing many children to wake suddenly and struggle to fall back asleep. Young children may cry or call out repeatedly during the night. Crying can further tighten the airway, making the cough sound harsher and prolonging sleep disturbance.

10. Recurring Restlessness

Children with croup often show recurring restlessness, particularly at night. Swelling around the voice box and windpipe can make breathing feel tight. Even mild breathing issues can disrupt sleep, making the child toss and turn or sit up to catch their breath. Discomfort from a barking cough or congestion can also contribute to repeated awakenings.

Temperature changes, such as a warm room or fever, may further increase nighttime restlessness. Noise, bright lights, or other environmental distractions can also make it harder for children to stay settled. Crying can briefly worsen airway swelling, which increases noisy breathing and distress. This can create a cycle in which breathing sounds trigger anxiety, and anxiety further intensifies breathing difficulty.

Children may wake frequently and seem unsettled, and this pattern can continue for several nights as the illness progresses. Adults with croup, though less common, may feel restless and change positions often due to throat tightness and a harsh cough.

11. Nausea

Nausea is not a primary symptom of croup, but it can occur in some children. It most often follows repeated or forceful coughing, which can irritate the stomach and trigger the gag reflex. Some children may vomit after a severe coughing episode. Swallowing excessive mucus during coughing can also contribute to stomach discomfort and feelings of nausea.

Anxiety or distress from difficulty breathing can further worsen feelings of nausea in some children. Overtiredness from poor sleep during illness can also make nausea more likely. When fever is present, appetite often decreases. Mild fever is common with viral croup, and reduced food or fluid intake can make nausea more noticeable.

Children may say they feel sick to their stomach, while younger ones may refuse food or drinks. Adults with croup may also experience nausea, particularly if throat irritation and coughing are severe. Even so, nausea is less common than breathing-related symptoms such as a barking cough or noisy breathing.

12. A Weakened Immune System

A weakened immune system can make croup symptoms more intense and longer lasting. The immune system normally helps control the viral infection that causes airway swelling. When this response is reduced, the body may struggle to limit inflammation.

Some people have weakened immunity due to chronic illness, recent infections, or medical treatments. Others take medications that suppress immune function, lowering the body’s ability to fight common respiratory viruses.

Croup often begins with mild cold-like symptoms such as a runny nose or low fever. In children and adults with weakened immune systems, early signs can quickly develop into a severe barking cough and noisy breathing due to swelling in the voice box and windpipe.

Young children face higher risk because their airways are already narrow, so even small amounts of swelling can interfere with breathing. Adults with reduced immune function may also experience more severe symptoms than expected.

13. General Body Pain

General body pain can occur with croup when a viral infection affects the body as a whole. The same virus that causes a barking cough and hoarse voice can trigger an immune response that leads to muscle and joint soreness. Inflammatory chemicals released during the immune response may contribute to the sensation of aches and stiffness.

Fatigue from poor sleep and frequent coughing can also make body pain feel more pronounced. These aches often appear early in the illness and are commonly accompanied by other cold-like symptoms such as a low-grade fever, runny nose, or sore throat. Fever can intensify body pain by increasing overall inflammation and energy use.

Children may not clearly describe body pain. Instead, they may seem tired, fussy, or less active than usual, avoid moving, or complain that their legs or back hurt. Adults with croup more often describe aching muscles similar to those felt during a cold or flu.

14. Asthma Attacks

Asthma attacks can look similar to croup, especially in children, because both cause coughing and breathing difficulty. However, asthma affects the lower airways in the lungs, while croup involves the upper airway near the voice box.

Unlike croup, asthma symptoms are often recurrent and can worsen at night or early in the morning. Asthma attacks may also develop gradually after exposure to triggers, rather than appearing suddenly like a croup’s barking cough. During an asthma attack, the lower airways become inflamed and narrow. The surrounding muscles tighten, and extra mucus forms, making it harder for air to move in and out of the lungs.

Wheezing, chest tightness, and shortness of breath are common features. Some children may breathe faster than usual or use extra chest and neck muscles when trying to move air through narrowed airways. Common triggers include cold air, exercise, smoke, dust, pet dander, and respiratory infections. Asthma affects both children and adults, and symptoms may appear more severe in children because their airways are smaller.