Severe Flu Symptoms: When to Seek Emergency Care | One Healthy Boston

The Flu

Severe Flu Symptoms: When to Seek Emergency Care

It’s that time of year again. Someone starts sniffling at home or in the office and before you know it, flu season is in full force. Many of us are all-too-familiar with the aches, fevers and irritating cold-like symptoms that come with the flu, but when do these “typical” side effects become more concerning?

Flu vs Common Cold

Many patients mistake influenza, or the flu for a bad cold. Identifying the flu in its early stages can be rather tricky, as many of the symptoms are similar to those associated with the common cold. Generally speaking, common cold symptoms are much milder than those of the flu, but there are a few other key differences that can help us distinguish between the two illnesses.

Onset – Unlike the common cold, which can develop gradually over the course of a few days, flu symptoms are abrupt. Most flu patients report feeling well the day before or even earlier in the day and then experience sudden and intense symptoms. Influenza is a virus that acts quickly, and unfortunately, so do its side effects.

Symptoms – Influenza and the common cold share some similar symptoms.  Sneezing, coughing and sore throats are common for both illnesses.  However, sudden or high fevers with marked with  generalized muscle aches and “chills” are especially typical of the flu. Vomiting and diarrhea are also known signs of the flu, although they typically affect children more so than adults.

Duration – In most cases, flu symptoms appear between 1-4 days after initial exposure. Again, these symptoms often appear suddenly. Symptoms will generally last between 5 to 7 days. For some, feelings of fatigue may linger for a few days after the other symptoms have been resolved. For those who have had the flu shot, symptoms often resolve sooner, and are often much less severe.


A majority of flu cases can be treated safely and effectively at home if patients get plenty of rest, replenish their fluids and take over-the-counter pain and fever reducers like ibuprofen (brand names Advil or Motrin) or acetaminophen (brand name Tylenol).  In select cases, anti-viral medication may be prescribed.

Red Flags

The flu virus can occasionally lead to serious complications. This is especially true for more vulnerable populations, including infants and small children under the age of 2, women who are pregnant or up to 2 weeks postpartum, those with certain chronic medical conditions, or adults over the age of 65.

Seek medical attention immediately if any combination of the following symptoms come into play.

All ages:

  • Difficulty breathing
  • Fainting or confusion
  • Chest pain
  • Severe neck stiffness or pain with fever
  • High fever that persists more than 2-3 days
  • Intractable vomiting
  • Fevers paired with rashes
  • Bluish or ashen skin coloring

For infants and small children, some additional flags:

  • Dehydration (no wet diapers)
  • Unusually inconsolable crying or fussiness

Seeking Medical Attention

If experiencing any life-threatening illness, patients are advised to go to the nearest emergency department. Otherwise, patients are encouraged to utilize nearby urgent care centers or their primary care provider.

Health Express, part of South Shore Health and other affiliated urgent care centers are equipped to treat both children and adults for a variety of urgent, or non-life-threatening, illnesses. Health Express is staffed with board-certified emergency medicine physicians, as well as emergency medicine-experienced physician assistants and nurse practitioners. These centers have onsite X-ray and laboratory testing capabilities and utilize a network of specialists who are available for consult and additional care.

Contact the South Shore Health Express at 781-626-5160 or visit for more information on your emergency treatment options.

Share this article