Side effects includes: pain in the abdomen, light sensitivity, dizziness, mania, and mood fluctuation. While using guan ye lian qiao (St. John's wort), to prevent drug interaction, avoid using the following drugs: cyclosporine theophyline warfarin
St. John's Wort has been shown to significantly lower indinavir (Crixivan) levels by almost 60%. St John's wort is a strong cell pigment P450 (CYP)3A4 revulsive. Using CYP3A4 medication and cause the level of medicine in the blood to drop to below the therapy level, thus require to increase the dosage of the medication. St John's wort can also trigger serotonin syndromes. It is due to the fact of using St John's wort with serotonin uptake inhibitors (like Prozac) or serotonin enhancing medication (like triptans) can increase the effect of uptake or the effect of enhancement of the medication. There are reports of 45 cases of serotonin syndromes caused by St John's wort. The most common side effects those of central nervous system, peripheral nervous system sickness and mental sickness. Among the mental sickness, 2 cases were suspected the result of using this herb with sertraline hydrochloride (a mood medicine). One case of serotonin syndromes was suspected the the result of the combination of the use of venlafaxine hydrochloride. Two cases of mania were suspected the use of this herb of lithium salt and the other case were suspected the use of this herb with Wellbutrin XL 副作用: 腹痛，對陽光敏感，暈眩，躁狂，情緒變化等。 為 了 避 免 药物相互作用﹐服用貫葉連翹, ﹐ 須避免服用以下藥物﹕ 環孢霉素（cyclosporine 防止器官移植排斥藥物）， 茶碱（theophyline 中樞興奮藥；舒張平滑肌藥 ）， 香豆素（warfarin 抗凝血藥）
貫葉連翹 能降低 療 艾滋病 的藥物﹐“佳息患”(indinavir/Crixivan) 亦稱 “克濾滿”幾乎至60%。 貫葉連翹是一種細胞色 素 P450 (CYP)3A4強誘導劑；與CYP3A4底物合用，可使這些藥的血濃度降至治療水平以下，因此需相應增加劑量。貫葉連翹可誘發５羥色胺（5-HT） 綜合征。因為貫葉連翹與 5-HT再攝取抑制劑或增強 5-HT活性的其他藥 (例如 triptans) 合用，對 5-HT再攝取的抑制作用有所增強。懷疑貫葉連翹引起的不良反應報告有45例。最常見的不 良反應為中樞神經、外周神經系統疾病和精神病。在精神病反應中，２例懷疑為5-HT 綜合症（與捨曲林相互作用的結果），１例有提示 5-HT綜合症的 症狀（與文拉法辛相互作用的結果）。懷疑貫葉連翹引起的躁狂症２例（１例與鋰劑合用，另１例與安非他酮合用）。 | 