However , some sedating antihistamines such as orphenadrine can produce a synergistic pain relieving effect permitting smaller doses of opioids be used .
Non-sedating antihistamines such as fexofenadine are often preferred as they avoid increasing opioid induced drowsiness .
Some sedating antihistamines such as orphenadrine can produce a synergistic pain relieving effect permitting smaller doses of opioids be used .
Non-sedating antihistamines such as fexofenadine are often preferred as they avoid increasing opioid induced drowsiness .