For the Meds you're taking (Effexor XR / Venlafaxine Hydrochloride) the following side effects have been reported regarding the respiratory system:
Frequent: cough increased, dyspnea
Infrequent: asthma, chest congestion, epistaxis, hyperventilation, laryngismus, laryngitis, pneumonia, voice alteration
Rare: atelectasis, hemoptysis, hypoventilation, hypoxia, larynx edema, pleurisy, pulmonary embolus, sleep apnea.
Additionally, people who had been diagnosed with GAD (general anxiety disorder) also reported these side effects during a trial: Abnormalities of sexual function (abnormal ejaculation and impotence), gastrointestinal complaints (nausea, dry mouth, anorexia, and constipation), problems of special senses (abnormal vision), and sweating.