Venlafaxine is a type of antidepressant called a serotonin-norepinephrine reuptake inhibitor. This medication is used to treat certain mental illnesses, including depression and anxiety. Venlafaxine interactions can occur if the medication is taken in conjunction with certain types of pain relievers and other antidepressants, as well as the herb St. John’s wort. Alcohol can also cause venlafaxine interactions, because it can exacerbate the side effects of the drug. For this reason, alcohol should be used cautiously.
This medication can cause unpleasant and potentially dangerous side effects if other types of antidepressants are also being taken. These venlafaxine interactions are part of a condition known as serotonin syndrome. This syndrome can occur when a serotonin-norepinephrine reuptake inhibitor is taken in conjunction with another antidepressant type called a selective serotonin reuptake inhibitor (SSRI). Symptoms of serotonin syndrome, which include mental confusion, hallucinations shivering, sweating, tremors, and increased heart rate, develop because there is too much serotonin in the body.
St. John’s wort, a popular herb, can cause a similar, but milder, type of serotonin syndrome. This herb is sold over-the-counter as a natural treatment for depression, and is even prescribed by doctors in some countries. Despite its popularity, it should still be used with caution, as serotonin syndrome can be dangerous even if caused by St. John’s wort.
Venlafaxine interactions can occur if the person taking this antidepressant is also using the pain-reliever tramadol. This medication is an opioid analgesic which is used to treat conditions such as restless leg syndrome and fibromyalgia, in addition to treating moderate to severe pain. Tramadol works by altering the availability of serotonin and norepinephrine in the brain, and can interfere with the activity of venlafaxine, which also affects these two neurotransmitters. When these medications are taken together, the seizure threshold of the brain is reduced, which means people taking these medications have an increased risk of seizures. Certain antidepressants, such as bupropion, can also have a similar effect.
People who work in occupations where drug testing of urine is carried out on employees should be aware that venlafaxine interactions can cause urine to test positive for the recreational drug phencyclidine, or PCP. Several scientific journals, including the American Journal of Psychiatry and Clinical Chemistry have published reports indicating that some brands of rapid-testing urine analysis kits can produce these false positive results. Someone who is taking this drug might, therefore, inform his or her employer if any work-related drug testing is carried out.