Can stimulants, such as methylphenidate (Ritalin) or amphetamine, contribute to enuresis?

Stimulants and Enuresis: A Complex Relationship

Stimulants can both contribute to and potentially improve enuresis, with methylphenidate having documented cases of causing enuresis as an adverse effect in some children with ADHD, while paradoxically improving enuresis in others. 1

Mechanisms and Evidence

The relationship between stimulants and enuresis is complex and appears to be bidirectional:

• Stimulant-induced enuresis: Case reports document that methylphenidate (MPH) can cause enuresis as an adverse effect in some children with ADHD 1. This contradicts older theories that stimulants might universally help enuresis.

• Stimulant improvement of enuresis: Paradoxically, some studies show that methylphenidate treatment can improve enuresis in certain children with comorbid ADHD and enuresis 2, 3. One study found that 75% of children with both ADHD and enuresis showed improvement in both conditions after 6 months of methylphenidate treatment 2.

Clinical Considerations

When evaluating a patient with enuresis who is taking stimulants:

1. Determine the temporal relationship:

   • Did enuresis begin after starting stimulant medication?
   • Did pre-existing enuresis worsen after stimulant initiation?
   • Has enuresis improved with stimulant therapy?

2. Consider the type of enuresis:

   • Primary (never achieved dryness) vs. secondary (developed after period of dryness)
   • Monosymptomatic vs. non-monosymptomatic
   • The deep sleep theory may be more applicable to secondary enuresis 3

3. Evaluate for psychosocial factors:

   • Enuresis can be assumed to be of psychological origin when a previously dry child begins wetting during periods of stress (e.g., parental divorce, school trauma, abuse, hospitalization) 4
   • Stimulants may interact with these psychological factors

Management Approach

If enuresis appears to be stimulant-induced:

1. Medication adjustments:

   • Consider adjusting the timing of stimulant administration 5
   • Evaluate if splitting doses or changing administration timing prevents rebound effects that might contribute to enuresis 5
   • Consider alternative ADHD medications if appropriate

2. First-line treatments for enuresis:

   • Conditioning therapy using a modern, portable alarm system is highly effective as first-line treatment for enuresis 4
   • Supportive approaches including education, demystification, and ensuring parents do not punish the child for enuretic episodes 4

3. Pharmacological options for enuresis:

   • DDAVP (desmopressin) - synthetic analogue of antidiuretic hormone that decreases urine production at night 4, 6
   • Imipramine - has been used for many years, though the mechanism of action in enuresis is unknown 4, 6
   • Note: Be cautious with imipramine due to potential cardiac effects and toxicity in overdose 4, 7

Important Caveats

• Monitor for side effects: When using stimulants, monitor vital signs as they can increase heart rate and blood pressure in some individuals 4

• Consider comorbidities: Evaluate for other medical conditions that may contribute to enuresis, such as sleep apnea, as surgical correction of upper airway obstruction has led to improvement or cure of enuresis 4

• Avoid medication interactions: MAO inhibitors must not be used with stimulants due to risk of severe hypertension 4

• Be aware of contradictory evidence: The literature contains contradictory findings regarding the relationship between methylphenidate and enuresis 1, suggesting individual patient factors play an important role

In summary, while stimulants can cause enuresis in some patients, they may improve it in others, particularly those with comorbid ADHD and enuresis. A careful assessment of the temporal relationship between stimulant initiation and enuresis onset/worsening is essential for determining the appropriate management strategy.