Working out is supposed to make you feel good, but sometimes you can experience some unpleasant and downright frightening side effects like dizziness, nausea, or blurry vision. To get some answers on these matters, we turned to a board-certified physician for advice.

We've been getting many questions from readers regarding odd symptoms experienced during and immediately after exercise. One reader experienced nausea, vomiting, and dizziness while exercising, which made her feel like she was going to black out, and another reader went running in 90 degree temperatures and developed exhaustion, blurry vision, imbalance, and impaired hearing. I'm sure that there are other readers out there who have had similar feelings when working out (including me) and wondered what the causes could have been. Typically, it's hard to diagnose exactly what happened to each of these readers, but there are only so many common causes of these types of symptoms that are related to exercise. The most common causes of these types of symptoms include dehydration, low blood sugar levels, overexertion, and quite possibly, heat exhaustion.

If you've ever experienced these symptoms, learn how to prevent them when you read more.

Whether you're doing high intensity workouts or just working up a sweat walking your dog, hydration is important. The definition of dehydration is when you lose more fluid than you take in, so the body does not having enough water and other fluids to carry out its normal functions. It's obvious that with any form of exercise, fluid will be lost from sweating, however in moderate to intense physical activity, the fluid loss will be much greater. Symptoms of mild to moderate dehydration include: dry and sticky mouth, fatigue, thirst, decreased urine output, muscle weakness, headache, and dizziness. Symptoms of severe dehydration (which is a medical emergency) are: extreme thirst, irritability/confusion, dry mouth and mucous membranes, lack of sweating, little to no urination, sunken eyes, low blood pressure, rapid heartbeat, and possibly unconsciousness.

Dehydration is best treated with rehydration! Water is typically the best bet in terms of rehydrating, but sports drinks containing electrolytes and carbohydrates are also appropriate. One way to prevent dehydration is to anticipate fluid loss during exercise by consuming fluids prior, during, and after exercise. Speaking with your physician or a registered dietitian certified in sports nutrition can help you formulate an individualized plan for adequate sports hydration.

Often, exercise-induced nausea or light-headedness can be secondary to high-intensity workouts or overexertion. Pushing too hard or performing exercise that is at a pace higher than one's fitness level are common causes of overexertion leading to nausea or light-headedness. I know sometimes I've pushed it too hard at spinning class towards the end of class and I've literally felt like I was going to throw up in front of the whole class. While pushing yourself to reach higher levels of fitness is important for many people so they can reach their goals, you must be careful to slowly increase your level of fitness and reach your goals over time.

Another cause of the symptoms our readers have asked about is hypoglycemia. Hpoglycemia is a condition when the blood glucose (sugar) level is too low. Hypoglycemia occurs when your body’s blood sugar is used up too quickly, glucose is released into the blood stream too slowly, or too much insulin is released into the bloodstream. Hypoglycemia is a common occurrence in people who have diabetes, however, it can happen to nondiabetics as well if not enough fuel (food) is consumed prior to exertion or exercise.

According to the University of Maryland Medical Center, symptoms of hypoglycemia include: headache, excessive sweating, blurred vision, dizziness, lack of coordination/imbalance, anxiety, mental confusion, heart palpitations, slurred speech, fatigue, and more seriously, seizures or coma. People who exercise in the mornings without eating anything or not much at all are at high risk of developing hypoglycemia. Prior to exercise, eating either a small meal or a hearty snack containing lean protein, a small amount of healthy fat, and complex carbohydrates can help prevent hypoglycemia. It is important to treat hypoglycemia immediately, by consuming food high in carbohydrates/sugar such as orange juice or bread.

Hopefully, by understanding and knowing about the most common causes of nausea/vomiting, dizziness, and weakness secondary to exercise, you can help prevent them by taking good care to keep yourself well-hydrated and well-nourished! If you experience any of the symptoms that I've discussed above on a frequent basis, it would be prudent to see your primary care physician to discuss proper evaluation and treatment.

DrSugar's posts are for informational purposes only and should not be considered medical advice, diagnosis, or treatment recommendations. Click here for more details.