symptoms of withdrawal from effexor
Consequently, it is not possible to provide a meaningful estimate of the proportion of individuals experiencing adverse events without first grouping similar types of untoward events into a smaller number of standardized event categories.
In the tabulations that follow, reported adverse events were classified using a standard COSTART-based Dictionary terminology. If the COSTART term for an event was so general as to be uninformative, it was replaced with a more informative term. All reported events are included except those already listed in Table 2 and those events for which a drug cause was remote. Risk factors for the development of SSRI- associated hyponatremia including advanced age, female gender, concomitant use of diuretics, low body weight, and lower baseline serum sodium levels have been identified. A case of increased libido and spontaneous erections has also been reported.
Although rare, several cases of venlafaxine- induced urinary symptoms including nocturia, enuresis, increased urge/frequency, and incontinence have been reported. There are not sufficient data with the use of venlafaxine extended-release at doses above 300 mg/day to determine the incidence of sustained increases in blood pressure at these high doses.
One study has reported average systolic blood pressure increases of 1.7 to 3.4 mm Hg and average diastolic pressure increases of 0.4 to 2.6 mm Hg. Although these events occurred during treatment with venlafaxine, causality has not been determined.
Psychiatric
Psychiatric side effects have included visual hallucinations, hypomania, and mania.
Psychiatric side effects reported in premarketing Phase 3 trials have included emotional lability, delusions, euphoria, hallucinations, manic reaction, psychosis, suicidal ideation, abnormal/changed behavior, homicidal ideation, paranoid reaction, and psychotic depression. There are not sufficient symptoms of withdrawal from effexor with the use of venlafaxine extended-release at doses above 300 mg/day to determine the incidence of sustained increases in blood pressure at these high doses.
One study has reported average systolic blood pressure increases of 1.7 to 3.4 mm Hg and average diastolic pressure increases of 0.4 to 2.6 symptoms of withdrawal from effexor Hg. Hyponatremia tends to develop within the first few weeks of symptoms of withdrawal from effexor (range 3 to 120 days) and typically resolves within 2 weeks (range 48 hours to 6 weeks) after therapy has been discontinued with some patients requiring treatment. Following discontinuation of therapy the amount of REM sleep tends to rebound. There are not sufficient data with the use of venlafaxine extended-release at doses above 300 mg/day to determine the incidence of sustained increases in blood pressure at these high doses.
One study has reported average systolic blood pressure increases of 1.7 to 3.4 mm symptoms of withdrawal from effexor and average diastolic pressure increases of 0.4 to 2.6 mm Hg. Consequently, it is not possible to provide a meaningful estimate of symptoms of withdrawal from effexor proportion of individuals experiencing adverse events without first grouping similar types of untoward events into a smaller number of standardized event categories.
In the tabulations that follow, reported adverse events were classified using a standard COSTART-based Dictionary terminology. The onset of venlafaxine- associated interstitial pneumonitis has ranged from 1 to 18 months after initial exposure to the drug and symptomatic symptoms of withdrawal from effexor occurred after discontinuation of venlafaxine and symptoms of withdrawal from effexor with corticosteroids.
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More Effexor resources
Effexor Detailed Consumer Information (PDR)
Effexor Prescribing Information (FDA)
Effexor Consumer Overview
Effexor Advanced Consumer (Micromedex) - Includes Dosage Information
Effexor MedFacts Consumer Leaflet (Wolters Kluwer)
Venlafaxine Prescribing Information (FDA)
Effexor XR Prescribing Information (FDA)
Effexor XR Extended-Release Capsules MedFacts Consumer Leaflet (Wolters Kluwer). The onset of withdrawal symptoms ranges from 14 to 48 hours after the last dose of venlafaxine extended-release and symptoms tend to resolve rapidly (range, within 2 to 24 hours) after resumption of therapy. All reported events are included except those already listed in Table 2 and those events for which a drug cause was remote. Tests for potential dose relationships for these events (Cochran-Armitage Test, with a criterion of exact 2-sided p-value ≤ 0.05) suggested a dose-dependency for several adverse events in this list, including symptoms of withdrawal from effexor hypertension, anorexia, nausea, agitation, dizziness, somnolence, tremor, yawning, sweating, and abnormal ejaculation.
TABLE 3 Treatment-Emergent Adverse Experience Incidence in a Dose Comparison Trial
Effexor (mg/day)
Body System/ Preferred Term
Placebo (n=92)
75 (n=89)
225 (n=89)
375 (n=88)
Body as a Whole
Abdominal pain
3.3%
3.4%
2.2%
8.0%
Asthenia
3.3%
16.9%
14.6%
14.8%
Chills
1.1%
2.2%
5.6%
6.8%
Infection
2.2%
2.2%
5.6%
2.3%
Cardiovascular System
Hypertension
1.1%
1.1%
2.2%
4.5%
Vasodilatation
0.0%
4.5%
5.6%
2.3%
Digestive System
Anorexia
2.2%
14.6%
13.5%
17.0%
Dyspepsia
2.2%
6.7%
6.7%
4.5%
Nausea
14.1%
32.6%
38.2%
58.0%
Vomiting
1.1%
7.9%
3.4%
6.8%
Nervous System
Agitation
0.0%
1.1%
2.2%
4.5%
Anxiety
4.3%
11.2%
4.5%
2.3%
Dizziness
4.3%
19.1%
22.5%
23.9%
Insomnia
9.8%
22.5%
20.2%
13.6%
Libido decreased
1.1%
2.2%
1.1%
5.7%
Nervousness
4.3%
21.3%
13.5%
12.5%
Somnolence
4.3%
16.9%
18.0%
26.1%
Tremor
0.0%
1.1%
2.2%
10.2%
Respiratory System
Yawn
0.0%
4.5%
5.6%
8.0%
Skin and Appendages
Sweating
5.4%
6.7%
12.4%
19.3%
Special Senses
Abnormality of accommodation
0.0%
9.1%
7.9%
5.6%
Urogenital System
Abnormal ejaculation/orgasm
0.0%
4.5%
2.2%
12.5%
Impotence
0.0%
5.8%
2.1%
3.6%
(Number of men)
(n=63)
(n=52)
(n=48)
(n=56)
Adaptation to Certain Adverse Events
Over a 6-week period, there was evidence of adaptation to some adverse events with continued therapy (eg, dizziness and nausea), but less to other effects (eg, abnormal ejaculation and dry mouth).
Vital Sign Changes
Effexor (venlafaxine hydrochloride) treatment (averaged over all dose groups) in clinical trials was associated with a mean increase in pulse rate of approximately 3 beats per minute, compared to no change for placebo. Although these events occurred during treatment with venlafaxine, causality has not been determined.
There have been postmarketing reports of angioedema.
Genitourinary
One case of symptoms of withdrawal from effexor orgasm and subsequent ejaculation with no erection as well as orgasmic episodes with no ejaculation or erection has also been reported. All reported events are included except those already listed in Table 2 and those events for which a drug cause was remote. The manufacturer recommends that therapy be discontinued in patients who develop seizures.
The impact of venlafaxine on pain summation may indicate a potential analgesic effect for clinical neuropathic pain.
Nearly all selective serotonin reuptake inhibitors, mixed serotonin/norepinephrine reuptake inhibitors, and tricyclic antidepressants cause sleep abnormalities to some extent. Some of these drugs (i.e., bupropion, mirtazapine, nefazodone, trazodone, trimipramine) appear to have a modest or minimal effect on REM sleep.
Cardiovascular
There are reports of sustained hypertension (some requiring immediate treatment). Although these events occurred during treatment with venlafaxine, causality has not been determined. There have been reports of increases in prothrombin time, partial thromboplastin time, or INR when venlafaxine was given to patients receiving warfarin therapy.
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Side Effects by Body System
Gastrointestinal
Gastrointestinal side effects have frequently included nausea (up to 35%), dry mouth (14% to 18%), constipation (12%), anorexia (12% to 23%), vomiting, diarrhea (5% symptoms of withdrawal from effexor 12%), eructation, abdominal pain, and flatulence.
Gastrointestinal side effects reported in premarketing Phase 3 trials have included symptoms of withdrawal from effexor appetite, bruxism, colitis, dysphagia, tongue edema, esophagitis, gastritis, gastroenteritis, gastrointestinal ulcer, gingivitis, glossitis, rectal hemorrhage, hemorrhoids, melena, oral moniliasis, stomatitis, mouth ulceration, abdominal distention, biliary pain, cheilitis, cholecystitis, cholelithiasis, esophageal spasms, duodenitis, hematemesis, gastroesophageal reflux disease, gastrointestinal hemorrhage, gum hemorrhage, hepatitis, ileitis, jaundice, intestinal obstruction, liver tenderness, parotitis, periodontitis, proctitis, rectal disorder, salivary gland enlargement, increased salivation, soft stools, and tongue discoloration.
Nervous system
Nervous system side effects have frequently included dizziness (16%), somnolence (up to 14%), insomnia (11% to 25%), fatigue (11%), nervousness (9%), abnormal dreams, sleep abnormalities, tremor, depression, paresthesia, decreased libido, agitation, hypertonia, anxiety, delirium, and twitching. Risk factors for the development of SSRI- associated hyponatremia including advanced age, female gender, concomitant use of diuretics, low body weight, and lower baseline serum sodium levels have been identified. Dermatologic side effects reported in premarketing Phase 3 trials have included pruritus, acne, alopecia, contact dermatitis, dry skin, eczema, maculopapular rash, psoriasis, urticaria, brittle nails, erythema nodosum, exfoliative dermatitis, lichenoid dermatitis, hair discoloration, skin discoloration, furunculosis, hirsutism, leukoderma, miliaria, petechial rash, pruritic rash, pustular rash, vesiculobullous rash, seborrhea, skin atrophy, symptoms of withdrawal from effexor hypertrophy, skin striae, and decreased sweating.
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