Feeling unwell after swimming is common, with several potential explanations. Factors range from waterborne microorganisms and pool chemicals to the body’s own physiological responses. Understanding these causes helps identify why one might feel sick and take preventive measures.
Contaminated Water Exposure
Swallowing water contaminated with germs is a frequent cause of illness after swimming, often leading to what are known as Recreational Water Illnesses (RWIs). These illnesses can stem from various pathogens, including parasites like Cryptosporidium and Giardia, as well as bacteria such as E. coli and viruses like norovirus. Symptoms commonly include:
Diarrhea
Vomiting
Stomach cramps
Nausea
Cryptosporidium is a particularly resilient parasite, capable of surviving for days in properly chlorinated pools because it is highly chlorine-tolerant. Giardia and hepatitis A are also moderately tolerant to chlorine, while many bacteria like E. coli are killed much faster. These germs are often introduced into the water by infected swimmers; even a small amount of contaminated water can cause illness. Beyond gastrointestinal issues, RWIs can also manifest as:
Skin symptoms
Ear symptoms
Eye symptoms
Respiratory symptoms
Reactions to Pool Chemicals
Pool chemicals, primarily chlorine, can also cause adverse reactions in swimmers. Chlorine disinfects water by killing harmful bacteria, but it can irritate the eyes, skin, and respiratory system. This irritation is a sensitivity or irritant dermatitis, manifesting as red, itchy skin, rashes, or hives. Chlorine strips away the skin’s natural oils, leading to dryness and irritation.
When chlorine reacts with organic matter introduced by swimmers, such as sweat, urine, and skin cells, it forms chemical irritants called chloramines. Chloramines are responsible for the strong chemical odor often associated with pools and can cause respiratory symptoms like coughing, wheezing, and chest tightness when inhaled. These volatile compounds can accumulate in the air, especially in indoor pools with poor ventilation, leading to discomfort for swimmers and even pool staff. Eye irritation, including redness and sensitivity to light, is also a common complaint due to chlorine exposure.
Physiological Factors
Beyond external contaminants and chemicals, the body’s own responses to swimming conditions can contribute to feeling unwell. Dehydration is common, as swimming can lead to fluid loss through sweating, even though individuals may not perceive it due to being in water. Symptoms of dehydration include:
Thirst
Dry mouth
Fatigue
Dizziness
Nausea
Overexertion from intense or prolonged swimming can cause physical fatigue, leading to exhaustion, muscle soreness, and sometimes nausea or lightheadedness. The body expends significant energy, depleting reserves and leaving a swimmer drained. Furthermore, exposure to cold water can lead to mild hypothermia, where the body’s core temperature drops below 95°F (35°C). Symptoms include:
Uncontrollable shivering
Numbness
Loss of coordination
Mental confusion
When to Seek Medical Advice
While many post-swim discomforts resolve on their own, certain symptoms warrant medical attention. Consult a healthcare professional if symptoms like diarrhea, vomiting, or stomach pain persist for more than a few days or worsen. Severe or bloody diarrhea, a high fever, or signs of severe dehydration, such as lethargy, rapid heart rate, or confusion, require immediate medical evaluation.
Respiratory distress, including severe coughing, wheezing, or difficulty breathing, should also prompt a visit to a doctor. Additionally, any skin rashes that are particularly painful, widespread, or do not improve with home care may need professional assessment. Inform the healthcare provider about recent swimming activities to aid in diagnosis.