The flu, caused by the influenza virus, is an unfortunately common illness characterized by symptoms such as sore throat, body aches, muscle pain, fever, chills, fatigue and cough. Dizziness that accompanies the flu is most often related to dehydration. Young children and older adults are particularly vulnerable to dehydration. Flu-related dizziness might also be due to a complication of the illness or a medication side effect. In addition to young children and seniors, pregnant women and people with chronic health conditions are more susceptible to flu complications than the general population. Treatment varies depending on the cause of dizziness associated with the flu.
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The body loses water with a high fever, a common flu symptom. Vomiting and diarrhea also cause water loss. These digestive system symptoms occur most frequently in children with the flu but can also occur in adults. When more body water is lost than is taken in, dehydration develops. Dizziness occurs with dehydration due to reduced water in the circulation, which can cause a drop in blood pressure -- especially when rising to a sitting or standing position. People on water pills need to be especially careful of dehydration with the flu.
Dehydration is treated by increasing fluid intake, sipping fluids throughout the day, avoiding caffeine and alcohol, and taking over-the-counter fever reducers as needed. Medication to stop nausea or vomiting may also be recommended. It is especially important that children receive adequate fluids to replace lost sugars and salts, including breast milk, formula or rehydrating solution (Pedialyte) as appropriate for the child. Intravenous fluids may be needed to replenish body water with severe dehydration.
Medication Side Effects
Some people take over-the-counter medicines to relieve flu symptoms, such as cough or runny nose. Antihistamines are common ingredients in these products, including diphenhydramine (Benadryl) and brompheniramine (Dimetapp, Ala-Hist IR) and doxylamine, which is found in many multi-ingredient products (Alka-Seltzer Plus). Dizziness is a possible side effect of antihistamines, especially in older adults, people on blood pressure medication, and those with heart rhythm abnormalities or heart failure.
If you're taking an over-the-counter flu medication that includes an antihistamine and develop dizziness, talk with your doctor. Changing the dosage or the medicine you're taking may be all that's needed if that is the cause of your dizziness. Your doctor may want to see you, however, to make sure there isn't another problem causing your lightheadedness.
The flu sometimes leads to complications, some of which can trigger dizziness. Pneumonia, wherein infected air sacs in the lungs fill with fluid, is a leading complication of flu. Severe pneumonia can cause lightheadedness due to low blood pressure or too little oxygen in the blood. An inner ear infection, another possible complication of the flu, can lead to a spinning sensation and nausea. People with existing health problems, such as asthma, heart failure, diabetes and HIV, are more susceptible to complications from the flu.
Treatment for dizziness related to flu complications depends on the underlying cause. Antibiotics or antiviral flu medicines, such as oseltamivir (Tamiflu), zanamivir (Relenza) and peramivir (Rapivab), may be prescribed for flu-related pneumonia. Inner ear infections related to the flu are often treated with medicines to relieve dizziness and nausea, such as meclizine (Antivert, Bonine) and promethazine (Phenergan).
The flu can upset blood sugar balance in people with diabetes, which may lead to dizziness. The strain of the infection on the body can lead to dangerously high blood sugars, which can progress to a life-threatening metabolic crisis. Not eating normally with the flu can also cause very low blood sugars. In both cases, dizziness may develop along with other symptoms such as weakness, extreme thirst and confusion. A persistently high or low blood sugar accompanied by any of these symptoms requires immediate medical treatment, which is likely to include intravenous fluids and other medications, as needed.
Additionally, people with diabetes are at increased risk for flu complications that can lead to dizziness. A study published in July 2010 in "Diabetes Care" reported that people with diabetes who contracted influenza during the 2009 pandemic flu season were 3 times more likely to be hospitalized with complications, compared to people without diabetes.
Warnings and Precautions
While most people recover from the flu without incident, even otherwise healthy people can develop complications. Developing dizziness when you have flulike symptoms could indicate a complication -- or perhaps another illness that has similar symptoms. Contact your doctor as soon as possible if you have dizziness along with flu symptoms. It's also important to watch for warning signs that could indicate the need for immediate medical attention, including: -- Difficulty breathing or a worsening cough. -- Severe vomiting with an inability to keep down fluids. -- A sunken soft spot on the head of a baby. -- Stomach or chest pain. -- Fainting, confusion, irritability or difficulty waking up. -- Neck pain or the development of a rash. -- Fever that goes away but then returns.