<unk>  has little to no effect if opioids are not present. In people with opioids in their system, it may cause increased sweating, nausea, restlessness, trembling, vomiting, flushing, and headache, and has in rare cases been associated with heart rhythm changes, seizures, and pulmonary edema. Besides the side effects listed above,<unk>  also has other adverse events, such as other cardiovascular effects (hypertension, hypotension, tachycardia, ventricular fibrillation, ventricular tachycardia) and central nervous system effects, such as agitation, body pain, brain disease, and coma. In addition to these adverse effects,<unk>  is also contraindicated in people with hypersensitivity to<unk>  or any of its formulation components.<unk>  has been shown to block the action of pain-lowering endorphins the body produces naturally. These endorphins likely operate on the same opioid receptors that<unk>  blocks. It is capable of blocking a placebo pain-lowering response, if the placebo is administered together with a hidden or blind injection of<unk> . Other studies have found that placebo alone can activate the body's μ-opioid endorphin system, delivering pain relief by the same receptor mechanism as morphine.<unk>  should be used with caution in people with cardiovascular disease as well as those that are currently taking medications that could have adverse effects on the cardiovascular system such as causing low blood pressure, fluid accumulation in the lungs (pulmonary edema), and abnormal heart rhythms. There have been reports of abrupt reversals with opioid antagonists leading to pulmonary edema and ventricular fibrillation. Hypersensitivities<unk>  preparations may contain methylparaben and propylparaben and are inappropriate for use by people with a paraben hypersensitivity. If a person is sensitive to<unk> mefene or<unk> trexone,<unk>  should be used with caution as these three medications are structurally similar. Cross-sensitivity among these drugs is unknown. Preservative-free preparations are available for those with paraben hypersensitivities.
Naloxone
Esketamine
Eptazocine
Pentazocine
Flumazenil
Nalorphine
Ephedrine
Alfentanil