I have chronic tension headaches and migraines. I probably eat a bottle of ibuprofen
pretty much monthly (and this is someone who is terrified of all medicine). It's the only thing that really works, and it works well with no adverse effects (at least for me). If you're nervous about drug interactions just call a pharmacist, but there most likely won't be any (at least with psych meds). And because you don't take it often or ever, it should be very effective...

In addition to ibuprofen, massage, ice, and hot showers also help (if it's a tension headache) -- feel around for tender spots on your scalp, face, neck and give them a good rub, then apply ice and/or get in a nice hot shower and let the water loosen up and massage the muscles. Anything to relieve muscle tension and get the blood flowing