Common effects (1–10% incidence) include: 
* Abnormal dreams
* Anisocoria
* Anorgasmia
* Anxiety
* Arthralgia (joint pain)
* Constipation
* Decreased or increased appetite
* Diarrhea
* Dilated pupils
* Dizziness
* Dry mouth
* Excessive sweating
* Fatigue
* Impotence (erectile dysfunction)
* Libido changes
* Myalgia (muscular aches and pains)
* Paraesthesia (abnormal skin sensation)
* Pyrexia (fever)
* Restlessness
* Sinusitis (nasal congestion)
* Tremor
* Vomiting
* Yawning