Do Attention Deficit Hyperactivity Disorder (ADHD) medications cause constipation?

From the Guidelines

ADHD medications can cause constipation as a side effect, particularly stimulant medications, due to their activation of the sympathetic nervous system, which slows down gut motility and decreases intestinal secretions, as noted in the 2019 clinical practice guideline for the diagnosis, evaluation, and treatment of attention-deficit/hyperactivity disorder in children and adolescents 1.

Key Points to Consider

• Stimulant medications, such as methylphenidate and amphetamine-based medications, are more likely to cause constipation than non-stimulant medications like atomoxetine.
• The mechanism of constipation is related to the sympathetic nervous system activation, reduced appetite, and decreased fluid intake.
• Non-stimulant ADHD medications may also cause constipation, although less frequently than stimulants.
• Managing constipation in patients taking ADHD medications involves increasing water intake, consuming more fiber-rich foods, maintaining regular physical activity, and establishing consistent bathroom routines.

Management of Constipation

• Patients should increase water intake to at least 8 glasses daily.
• Consuming 25-30g of fiber-rich foods daily can help alleviate constipation.
• Regular physical activity and consistent bathroom routines are also recommended.
• If constipation persists, over-the-counter stool softeners or mild laxatives may be considered, but patients should consult their healthcare provider before adding any medications.
• Adjusting the ADHD medication dosage or switching to a different medication may also alleviate constipation while still effectively treating ADHD symptoms, as suggested by the 2019 guideline 1.

Important Considerations

• The 2019 clinical practice guideline for ADHD treatment highlights the importance of monitoring patients for potential side effects, including constipation, and adjusting treatment plans accordingly 1.
• While the evidence from the 2011 guideline 2 provides valuable insights into ADHD medication side effects, the more recent 2019 guideline 1 offers updated recommendations and should be prioritized in clinical decision-making.

From the FDA Drug Label

Among atomoxetine hydrochloride-treated patients, irritability (0.3%, N=5); somnolence (0.3%, N=5); aggression (0.2%, N=4); nausea (0.2%, N=4); vomiting (0.2%, N=4); abdominal pain (0.2%, N=4); constipation (0.1%, N=2); fatigue (0.1%, N=2); feeling abnormal (0. 1%, N=2); and headache (0.1%, N=2) were the reasons for discontinuation reported by more than 1 patient. The following reactions did not meet this criterion but were reported by more atomoxetine-treated patients than placebo-treated patients and are possibly related to atomoxetine treatment: ... constipation ...

Constipation is a possible side effect of atomoxetine, reported by 0.1% of patients, which is a relatively low incidence rate 3.

From the Research

ADHD Medications and Constipation

• There is evidence to suggest that certain ADHD medications may cause constipation, as reported in a case study of an 11-year-old male with ADHD who experienced constipation and retention of lisdexamfetamine dimesylate capsules in the gastrointestinal tract 4.
• The study found that the patient had approximately 20 capsules in the large intestine, which were likely causing the constipation, and that discontinuing the medication and administering saline enemas helped to resolve the issue.
• However, other studies have not specifically reported constipation as a common side effect of ADHD medications, instead focusing on other potential adverse effects such as cardiovascular problems 5, misuse of prescription stimulants 6, and combination pharmacotherapy for adult ADHD 7.
• One study did mention that prescription stimulants can have adverse effects, including dangers such as psychosis, myocardial infarction, cardiomyopathy, and even sudden death, but did not specifically mention constipation as a potential side effect 8.

Potential Mechanisms and Implications

• The exact mechanism by which ADHD medications may cause constipation is not fully understood, but it is possible that certain medications may affect gut motility or have other gastrointestinal effects.
• Further research is needed to fully understand the potential relationship between ADHD medications and constipation, as well as to determine the best course of treatment for patients who experience constipation while taking these medications.
• Clinicians should be aware of the potential for constipation as a side effect of ADHD medications and monitor patients accordingly, particularly those taking lisdexamfetamine dimesylate or other medications that may be associated with gastrointestinal effects 4.