Can Vyvanse (lisdexamfetamine) cause tongue numbness?

Tongue Numbness and Vyvanse (Lisdexamfetamine)

Tongue numbness is not a commonly reported side effect of Vyvanse (lisdexamfetamine) and is not listed in the FDA drug label or clinical guidelines for this medication.

Mechanism of Action and Known Side Effects

Lisdexamfetamine (Vyvanse) is a prodrug that is hydrolyzed to its active form d-amphetamine in the blood following oral administration 1. As a central nervous system stimulant, it works by:

• Inhibiting dopamine transporter (DAT) and noradrenaline transporter (NAT)
• Increasing dopamine and noradrenaline concentrations in the synaptic cleft
• Promoting the release of these neurotransmitters 1

The FDA-approved drug label for lisdexamfetamine documents the following common side effects 2:

• Decreased appetite (27-34%)
• Insomnia (13-27%)
• Dry mouth (26-36%)
• Weight loss (3-9%)
• Increased heart rate/blood pressure (2-7%)
• Anxiety (5-6%)
• Headache (30%)

Neurological Side Effects and Peripheral Vasculopathy

While tongue numbness specifically is not listed, Vyvanse can cause certain neurological and vascular effects that might be relevant:

1. Peripheral vasculopathy: The FDA label specifically mentions circulation problems in fingers and toes (Raynaud's phenomenon) that can cause numbness, coolness, pain, and color changes 2. This vasoconstrictive effect theoretically could affect other body parts with rich vascular supply, including the tongue.

2. Serotonin syndrome: The FDA label warns about the risk of serotonin syndrome with concomitant use of lisdexamfetamine and other serotonergic drugs 2. Serotonin syndrome can present with various neurological symptoms, although tongue numbness is not typically characteristic.

Clinical Implications and Recommendations

If a patient experiences tongue numbness while taking Vyvanse:

1. Evaluate for alternative causes: Consider other common causes of tongue numbness such as local trauma, dental issues, vitamin deficiencies (particularly B12), or other neurological conditions.

2. Monitor for additional symptoms: Watch for other signs of peripheral vasculopathy or allergic reactions.

3. Consider medication timing: Note if the symptom correlates with peak drug levels (approximately 3-4 hours after dosing) 3.

4. Document and report: Unusual side effects should be documented and reported to appropriate pharmacovigilance systems.

5. Consider consultation: If symptoms persist or worsen, neurological consultation may be warranted.

Conclusion

While tongue numbness is not explicitly listed among the known side effects of Vyvanse in the FDA label or clinical guidelines, the medication's vasoconstrictive properties and neurological effects could potentially manifest in this way in some individuals. Patients experiencing this symptom should discuss it with their healthcare provider for proper evaluation.