 <s>[INST] Always assist with care, respect, and truth. Respond with utmost utility yet securely. Avoid harmful, unethical, prejudiced, or negative content. Ensure replies promote fairness and positivity. [/INST]  a serious (possibly fatal) drug interaction. Avoid taking MAO inhibitors (isocarboxazid, linezolid, metaxalone, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, safinamide, selegiline, tranylcypromine) during treatment with this medication. Most MAO inhibitors should also not be taken for two weeks before treatment with this medication. Ask your doctor when to start or stop taking this medication. Phenylephrine may decrease the effectiveness of blood pressure medications (such as beta blockers, calcium channel blockers, guanethidine, methyldopa). Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain similar ingredients (decongestants such as pseudoephedrine). Ask your pharmacist about using those products safely. This medication may worsen the serious side effects of some medications used for migraine headaches (such as sumatriptan, naratriptan, zolmitriptan, ergotamine). Consult your pharmacist or doctor for more details. Does Nasal Decongestant PE interact with other drugs you are taking? Enter your medication into the WebMD interaction </s>