8 Illnesses That Cause Flu-Like Symptoms That Aren’t the Flu

Other bugs can also cause those flu-like symptoms.

At a Glance

• Numerous ailments can manifest with symptoms akin to the flu, including fever, cough, runny nose, and headaches. The majority of these infections typically resolve autonomously. It’s essential to remain vigilant for concerning indicators such as breathlessness, chest or abdominal discomfort, lightheadedness, or dehydration. Should you encounter any of these warning signs alongside your flu-like symptoms, it’s advisable to promptly contact a medical professional or visit an emergency medical facility.

Given the highly contagious nature of the flu, it’s natural to be concerned about any cough, muscle ache, or even a slight fever, interpreting them as potential signs of flu infection.

This reaction is understandable since a multitude of other illnesses can also produce flu-like symptoms such as fever, cough, runny nose, and headaches, among others. According to Cindy Weston, DNP, RN, FNP-BC, an associate professor at the Texas A&M School of Nursing, these symptoms can arise from any significant infection that triggers our immune system response.

In simpler terms, as Joseph Khabbaza, MD, a pulmonologist at the Cleveland Clinic, explains, most instances of the flu tend to resemble a common cold in terms of symptomatology. Moreover, it’s worth noting that flu vaccines can mitigate symptom severity in individuals who have been vaccinated.

The definitive method to confirm a flu diagnosis is through testing. However, at times, subtle cues can assist in distinguishing between the flu and other ailments. Notably, testing can also help differentiate between the flu and conditions like COVID-19.

To provide you with insights into various illnesses that mimic flu-like symptoms but aren’t actually the flu, here is essential information you should be aware of.

Colds

Colds and influenza are both caused by viral infections, sharing a common seasonal occurrence and displaying numerous similar symptoms, such as a sore throat and nasal congestion. The primary distinguishing factor lies in the speed of symptom development.

“Colds generally exhibit a gradual onset of symptoms, unfolding step by step over several days,” explained Keri Peterson, MD, a practicing internist in New York, in an interview with Health. “In contrast, the flu manifests a constellation of symptoms like high fever, cough, muscle aches, and profound fatigue within a span of 24 to 48 hours.”

Despite the extensive symptom overlap, certain indicators help differentiate colds from the flu. For instance, chest pain or body aches, which align more closely with the flu, are typically absent in cases of colds, as noted by Dr. Peterson.

Strep Throat

While the flu and strep throat exhibit several overlapping symptoms, there exist two distinct features that are commonly associated with the flu but rarely found in cases of strep throat: cough and nasal congestion.

Furthermore, strep throat may give rise to additional indications such as enlarged lymph nodes (small, immune system-related structures), swollen tonsils (soft masses of tissue located at the throat’s rear), small red spots on the roof of the mouth, or the presence of white patches on the tonsils called exudates. Remarkably, none of these manifestations are typical of flu infections.

In scenarios where a healthcare professional suspects strep throat, they are likely to perform a throat swab and subsequently conduct a bacterial test. Upon a positive test result, antibiotics are often prescribed, effectively addressing the symptoms in a relatively swift manner.

Pneumonia

Pneumonia can manifest either independently from the flu or as a subsequent complication arising from an initial illness. It’s possible to seemingly recover from the flu only to be afflicted by another infection.

“People may endure the flu and appear to have overcome it, but approximately a week later, they might present with pneumonia,” remarked Cindy Weston, highlighting this observation.

Pneumonia that accompanies or follows the flu can stem from the flu virus itself or result from co-infections involving both the flu virus and bacteria. Notably, bacterial pneumonia represents a grave concern and necessitates treatment through antibiotics.

In cases of bacterial pneumonia, Cindy Weston elaborated, “Persistent and unrelenting coughing, often accompanied by chest discomfort, characterizes the condition. Fever might vary from low-grade to higher levels. Pneumonia also tends to suppress appetite and may induce body aches.” Notably, a cough associated with pneumonia tends to be productive with mucus.

Comparatively, viral pneumonia typically presents as less severe than its bacterial counterpart. Symptoms may include congestion, persistent coughing, and heightened fatigue.

To discern possible signs of pneumonia, healthcare professionals can employ a stethoscope to listen for specific indications on the chest, as suggested by Dr. Keri Peterson.

Mononucleosis

Mononucleosis, commonly referred to as the “kissing disease” or mono, is transmitted primarily through saliva, as well as via coughing, sneezing, and the sharing of utensils.

Mono is primarily triggered by the Epstein-Barr virus and tends to affect adolescents and young adults more frequently than other age groups.

While symptoms of mono tend to emerge gradually, they can closely resemble those of the flu. Individuals might experience intense fatigue, a sudden fever, as well as a sore throat and body aches. Nonetheless, distinctive symptoms set mono apart from the flu, such as the potential presence of an enlarged liver or spleen.

In contrast to the flu, the duration of mono is prolonged, often persisting for two to four weeks, and occasionally extending even further, potentially lasting for several months.

Meningitis

Meningitis involves the inflammation of the protective membranes, known as meninges, that envelop the brain and spinal cord.

Comparable to pneumonia, meningitis can arise from either a viral or bacterial infection. Viral meningitis is more prevalent and tends to be milder, yet the symptoms of both viral and bacterial forms share similarities with flu-like presentations: encompassing symptoms such as headaches, fever, and fatigue.

Additionally, meningitis is characterized by a stiff neck and heightened sensitivity to bright light.

Similar to the trajectory of colds and the flu, viral meningitis often follows a self-limiting course, with most individuals recovering within approximately a week. However, bacterial meningitis presents a more severe scenario, potentially leading to brain damage or fatality if not promptly addressed through antibiotic treatment.

Bronchitis

Acute bronchitis exhibits a striking resemblance to both cold and flu symptoms, largely because it is often caused by the same viruses that trigger those illnesses.

Dr. Peterson elaborates, “Bronchitis shares significant overlap with symptoms like a productive cough accompanied by mucus, fatigue, and a sore throat.” Notably, the primary distinction lies in the absence of elevated fever in cases of bronchitis.

Moreover, the focal point of bronchitis symptoms tends to be the chest and throat, in contrast to the comprehensive body aches characteristic of the flu. The persistent cough associated with acute bronchitis can linger for as long as three weeks, surpassing the duration of a cough stemming from the flu.

Unlike the flu, bronchitis doesn’t have a definitive diagnostic test, thereby necessitating healthcare providers to rely on symptom inquiry and physical examination for diagnosis. Treatment of bronchitis entails ample rest, fluid intake, and the administration of medications aimed at alleviating symptoms.

Respiratory Syncytial Virus (RSV)

The symptoms of respiratory syncytial virus (RSV) often mirror those of the flu (or a cold), leading to potential confusion.

As Afif El-Hasan, MD, a pediatrician associated with Kaiser Permanente in Orange County, California, explained, RSV can trigger a runny nose and cough, much like the flu or a cold.

However, unlike the flu, the onset of RSV symptoms is generally more gradual. Moreover, these symptoms typically abate on their own, requiring primarily increased fluid intake and ample rest for management.

Infections stemming from human parainfluenza viruses also yield similar symptoms, although they tend to be less severe compared to the flu.

In the words of Dr. El-Hasan, “They resemble the flu, albeit with milder effects.”

Human Immunodeficiency Virus (HIV)

Around two to four weeks following exposure to the human immunodeficiency virus (HIV), a majority of individuals undergo flu-like symptoms. These manifestations could encompass fever, chills, rashes, night sweats, and muscle aches. The duration of these symptoms can vary, ranging from a few days to several weeks.

While various factors can lead to flu-like symptoms, if there is a suspicion of potential HIV exposure, seeking testing is of paramount importance. The Centers for Disease Control and Prevention (CDC) also strongly advises HIV testing for all individuals aged 13 to 64, irrespective of whether flu-like symptoms are present or not.

When Should You Contact A Healthcare Provider?

“If you suspect you might have contracted the flu, it’s crucial to consult a healthcare provider within the initial 48 hours,” emphasized Dr. Peterson, underlining the significance of swift action due to the time-sensitive nature of the antiviral treatment. “Opt for a cautious approach.”

Dr. Khabbaza further advised that if your daily routine becomes hindered by symptoms, seeking medical attention is advisable. Moreover, if specific symptoms worsen, it could indicate the presence of the flu or a potentially severe ailment, rather than just a mild chest cold, warranting prompt medical assessment.

To illustrate, if body aches escalate “to the extent that they impede your mobility,” or if your symptoms result in breathing difficulties, promptly engaging with a healthcare provider becomes imperative, according to Dr. Khabbaza.

Particularly, symptoms like shortness of breath or chest pain should be heeded as they can signify various medical emergencies, including conditions like pulmonary embolism—an arterial blockage caused by a blood clot—necessitating immediate medical intervention.