Does duloxetine (Cymbalta) cause somnolence?

From the Guidelines

Duloxetine is known to cause somnolence as a common adverse effect, particularly at higher doses [ 1 ].

Common Side Effects

• Somnolence is reported as one of the common side effects of duloxetine, along with nausea, dry mouth, headache, decreased libido, dizziness, and insomnia [ 1 ].
• The incidence of somnolence tends to decrease with continued treatment, with most cases occurring within the first week of therapy.
• At lower doses, such as 20-60 mg daily, the incidence of somnolence is lower, affecting around 10% of patients [ 1 ].

Dose-Dependent Side Effects

• Higher doses of duloxetine, such as 60-120 mg daily, are associated with a higher incidence of somnolence, affecting around 12% of patients [ 1 ].
• The risk of somnolence is also increased when duloxetine is combined with other central nervous system depressants [ 1 ].

Patient Factors

• Patient factors, such as age, sex, and comorbidities, may also influence the risk of somnolence associated with duloxetine [ 1 ].
• Patients with a history of somnolence or sleep disorders may be more susceptible to the sedative effects of duloxetine [ 1 ].

From the FDA Drug Label

The most commonly observed adverse reactions in duloxetine delayed-release capsules-treated patients (as defined above) were: Diabetic Peripheral Neuropathic Pain: nausea, somnolence, decreased appetite, constipation, hyperhidrosis, and dry mouth Fibromyalgia: nausea, dry mouth, constipation, somnolence, decreased appetite, hyperhidrosis, and agitation. Chronic Pain due to Osteoarthritis: nausea, fatigue, constipation, dry mouth, insomnia, somnolence, and dizziness. Chronic Low Back Pain: nausea, dry mouth, insomnia, somnolence, constipation, dizziness, and fatigue The most commonly observed adverse reactions in duloxetine delayed-release capsules-treated patients in all the pooled adult populations (i.e., MDD, GAD, DPNP, FM, OA, and CLBP) (incidence of at least 5% and at least twice the incidence in placebo-treated patients) were nausea, dry mouth, somnolence, constipation, decreased appetite, and hyperhidrosis.

Yes, duloxetine (Cymbalta) can cause somnolence. It is listed as one of the most common adverse reactions in adult trials, with an incidence of at least 5% and at least twice the incidence in placebo-treated patients 2.

From the Research

Adverse Effects of Duloxetine

• The most common adverse events associated with duloxetine include nausea, dry mouth, headache, constipation, dizziness, and fatigue 3, 4, 5
• Somnolence is not explicitly listed as a common adverse event in the provided studies, but it is mentioned as a potential side effect of venlafaxine, a similar serotonin and norepinephrine reuptake inhibitor 4
• Duloxetine has been associated with other adverse effects, such as dysosmia and dysgeusia, in rare cases 6

Pharmacology and Mechanism of Action

• Duloxetine is a potent and selective inhibitor of serotonin and norepinephrine transporters, with a balanced profile of binding to both transporters 3, 4, 5
• The drug has a low affinity for other receptors and transporters, and does not inhibit monoamine oxidase types A or B 3
• Duloxetine's mechanism of action is thought to involve the inhibition of reuptake of serotonin and norepinephrine, leading to increased levels of these neurotransmitters in the central nervous system 7

Clinical Use and Efficacy

• Duloxetine is approved for the treatment of major depressive disorder, generalized anxiety disorder, diabetic peripheral neuropathic pain, and fibromyalgia 3, 4, 5
• The drug has been shown to be effective in clinical trials, with response and remission rates comparable to other marketed antidepressants 3, 4