The Crucial Role of Hydration in Recovery from Illness and Medication

When an athlete is ill—whether experiencing fever, vomiting, diarrhea, or a respiratory infection—the body’s usual fluid-electrolyte homeostasis is disrupted. This disruption can significantly undermine performance, recovery, and overall well-being. The following discussion examines the physiological challenges, practical implications, and strategic hydration interventions appropriate for athletes under these conditions.

Understanding Hydration Challenges

Elevated Fluid Loss and Increased Requirements

Illness triggers multiple pathways by which fluid losses increase and normal fluid needs shift upward. Fever and sweating raise insensible and evaporative losses; vomiting and diarrhea directly eliminate both fluids and solutes; appetite loss reduces intake. Some medications—such as diuretics or certain antihypertensives—further increase urine output or reduce fluid retention, increasing net fluid loss. Without compensatory intake, hypohydration can rapidly result.

Electrolyte Imbalance Risk

The accompanying loss of key electrolytes—particularly sodium and potassium—is often underestimated. Electrolytes govern fluid movement between intracellular and extracellular compartments, support neuromuscular function, and maintain osmotic and acid–base balance (Jäger et al., 2022). When illness or medication disrupts electrolyte handling or renal excretion patterns, the athlete becomes vulnerable to cramps, impaired muscle contraction, and broader systemic instability. Armstrong (2021) underscores that both sodium loss via sweat and inadequate replacement contribute to performance decrement and risk of hydration-related illness.

Impact on Performance, Immunity, and Recovery

The evidence is unequivocal: even modest hypohydration (≥2 % of body mass) impairs physical output, cognitive function, mood, and decision-making capacity (Adan, 2022). In team-sport athletes, body mass losses of 2–4 % have been associated with declines in sprint speed, technical skill, and high-intensity running capacity (Nassis et al., 2016). From an immune-recovery perspective, fluid deficits compromise circulation, nutrient delivery, and clearance of metabolic by-products, slowing healing and increasing susceptibility to further illness or injury.

Medication Interactions

Medication use—especially diuretics, blood-pressure agents, or gastrointestinal treatments (e.g., antibiotics, laxatives)—often influences fluid and electrolyte kinetics. Such medications may alter sweat and urine output, blunt thirst responses, or cause GI losses that complicate hydration strategies. As such, a one-size-fits-all hydration plan is insufficient when an athlete is ill or medicated; their plan must reflect altered physiology.

What the Research and Guidelines Indicate

Professional organisations and empirical research provide strong direction:

• The American College of Sports Medicine (ACSM) Position Stand recommends that athletes begin activity in a euhydrated state, limit body mass losses during exercise to less than 2 %, and drink fluids with electrolytes and carbohydrates during activity as needed (Sawka et al., 2007).

• Individualised hydration strategies – based on measuring sweat losses and electrolyte content – have been shown to improve fluid balance and performance over ad-libitum drinking (McCubbin et al., 2018).

• Monitoring methods such as body-mass change, urine specific gravity, and thirst ratings are validated field measures of hydration status (Armstrong et al., 2024).

• Research highlights that electrolyte-rich fluids (versus plain water) improve fluid retention and maintain plasma volume more effectively under stress (Hoffman et al., 2021).

Strategic Hydration for Athletes Recovering or On Medications

For an athlete who is recovering or taking medications that alter fluid-handling, the following architecture is recommended:

Scenario	Pre-Game / Pre-Tournament	During Play	Post-Game / Between Matches
Recovering/on medication	1. Baseline assessment (body weight, urine colour, urine specific gravity). 2. Begin hydrating earlier than usual; include an electrolyte beverage if sodium loss is elevated. 3. Review medication timing with medical staff.	1. Frequent, small sips; fluids should be accessible and appealing; ensure electrolyte-carbohydrate drink if heavy sweating. 2. Monitor for dizziness, cramps, dark urine, fatigue → reduce intensity if needed.	1. Aggressive rehydration: replace prior losses plus buffer if illness persists. Aim ~1.2-1.5 L per kg lost. 2. Include saline snacks or sodium-rich foods, fluids, and cooling/rest to reduce ongoing losses.

Protocol Suggestions

Sweat-and-Weight Test (non-competitive time): Athlete weighs in minimal clothing pre-training, records fluid consumed, weighs post-training (after toweling down). Difference indicates sweat rate and guides personalized fluid/electrolyte plan. Pre-Game Hydration Bolus: Two to three hours before competition, consume 500–750 mL of fluid with added sodium, especially if recovering from illness or GI losses. Split volume if still symptomatic. During Game / Between Matches: Offer small sips every 15–20 minutes; fluid temperature ~10-15 °C improves absorption and comfort (Sawka et al., 2007). If residual GI symptoms exist, ensure palatable flavors and avoid large fluid boluses. Post-Game Recovery Window: Within two hours, begin replacement—~150 % of fluid lost (e.g., 1 kg body mass = ~1.5 L fluid) over several hours, paired with salty snacks and hydrating foods (McCartney et al., 2017).

Risks to Be Aware Of

• Overhydration/Hyponatremia: Excess plain water intake without electrolyte replacement dilutes plasma sodium levels, which in extreme cases can lead to hyponatremia (Armstrong, 2021).

• Gastrointestinal Distress: Large fluid volumes too close to activity or in times of gut upset (vomiting, diarrhea) can provoke nausea or bloating.

• Medication Interactions: Certain medications may require fluid restrictions or timing adjustments; hydration plans must coordinate with medical advice.

Integrative Game-Day Example for a Recovering Athlete

Assuming a mild fever or GI episode, now mostly recovered but on a diuretic medication:

• Day Before / Morning: Emphasise fluids and electrolyte-rich snacks (e.g., broth, fruit). Avoid caffeine or diuretics that exacerbate fluid loss.

• 2-3 Hours Pre-Match: 500 mL electrolyte drink + salty snack (e.g., pretzels or light broth).

• Warm-Up / Immediately Pre-Kick: 200-300 mL small sip.

• During Match / Between Matches: Sip every quarter or interval; fluid ~6-8 % carbohydrate + sodium adjusted based on sweat loss; cold (~10-15 °C).

• Post-Match / Between Matches: Weigh ASAP; if 1 kg lost, aim ~1.25-1.5 L replacement; combine fluid + salty solid foods + cooling rest.

• Overnight: Continue moderate fluid intake; if diuretic effect persists, consider electrolyte-rich fluid pre-bed; sleep aids recovery.

Conclusion

For an athlete recovering from illness or managing medications, hydration is not an optional “nice-to-have”—it is foundational. A custom-tailored hydration plan that accounts for individual sweat rates, electrolyte losses, illness-related deficits and medication interactions will significantly enhance immune recovery, performance readiness and injury risk reduction. Track real metrics (body mass change, urine colour/SG, subjective thirst) rather than guessing. Avoid both under-hydration and over-hydration; balance fluid, electrolyte, rest and nutrition to support full recovery and return to peak performance.

References

Adan, A. (2022). Effects of hypohydration and fluid balance in athletes’ cognitive and team sport performance. Frontiers in Physiology, 13, Article 9382508. https://doi.org/10.3389/fphys.2022.9382508

Armstrong, L. E. (2021). Rehydration during endurance exercise: Challenges, research, options, methods. Nutrients, 13(3), 887. https://doi.org/10.3390/nu13030887

Hoffman, J. R., Beis, L. Y., Burgos, W., & Kellogg, M. (2021). Electrolyte supplementation does not necessarily protect athletes from illness associated with electrolyte imbalance. Stanford Medicine News. https://med.stanford.edu/news/all-news/2020/02/electrolyte-supplements-dont-prevent-illness-in-athletes.html

Jäger, R., Kerksick, C. M., Campbell, B., Cribb, P. J., Wells, S. D., Skwiat, T., … & Antonio, J. (2022). Importance of electrolytes in exercise performance and assessment: Blood and tissue components. Applied Sciences, 14(22), Article 10103. https://doi.org/10.3390/app142210103

McCartney, D., Dawson, B., Landers, G., zh, Z., Thomas, C., Dennis, S. (2017). The effect of fluid intake following dehydration on continuous exercise performance under heat stress. Sports Medicine – Open, 3, 7. https://doi.org/10.1186/s40798-017-0079-y

McCubbin, A., Boldy, M., Priestley, M., & Taylor, R. (2018). Individualised hydration plans improve performance outcomes for athletes. Journal of the International Society of Sports Nutrition, 15, Article 23. https://doi.org/10.1186/s12970-018-0230-2

Nassis, G. P., Routledge, H., Davies, B., Easton, C., Goodall, S., & Taylor, L. (2016). Fluid balance in team sport athletes and the effect of hypohydration on performance: A review. European Journal of Sport Science, 16(7), 885–894. https://doi.org/10.1080/17461391.2016.1190312

Sawka, M. N., Burke, L. M., Eichner, E. R., Maughan, R. J., Montain, S. J., & Stachenfeld, N. S. (2007). American College of Sports Medicine position stand: Exercise and fluid replacement. Medicine & Science in Sports & Exercise, 39(2), 377–390. https://doi.org/10.1249/mss.0b013e31802ca597

U.S. Heart Association. (2024, June 19). Electrolytes can give the body a charge—but try not to overdo it. American Heart Association News. https://www.heart.org/en/news/2024/06/19/electrolytes-can-give-the-body-a-charge-but-try-not-to-overdo-it

Coach Nicholas Serenati, founder of Royal United FC, is a USSF-licensed coach, Certified Strength and Conditioning Coach, and Certified Sports Performance Specialist. He provides elite soccer training focused on speed, agility, and player development, helping athletes maximize their performance on and off the field.