I herxed to high heaven and back on doxy. Rifampin is not a tetra family abx, and I was also on that. I was never on doxy and rifampin at the same time- I would have done nothing but lay in bed.

It could be that you are not getting the firepower from doxy that you were getting from mino. Not only because doxy has less penetration, but because rifampin reduces the effect of doxy. I posted this study on a different thread.

According to this study, doxy and rifampin are not a good combo.

"Possible implications of doxycycline-rifampin interaction for treatment of brucellosis
JD Colmenero, LC Fernandez-Gallardo, JA Agundez, J Sedeno, J Benitez and E Valverde
Internal Medicine Department, Malaga Regional Hospital, Spain.

We studied the possible interaction between rifampin and doxycycline in 20 patients with brucellosis treated randomly with either doxycycline and streptomycin or doxycycline and rifampin. The doxycycline levels in the plasma of patients in the group treated with rifampin were significantly lower than those in the plasma of patients treated with doxycycline and streptomycin. Furthermore, clearance in patients treated with rifampin was significantly higher than that in patients treated with doxycycline and streptomycin, and consequently, the elimination half-life and the area under the concentration-time curve were significantly lower. There was no therapeutic failure or relapse in the group treated with doxycycline and streptomycin, whereas 2 of 10 patients in the group treated with doxycycline and rifampin had a therapeutic failure or relapse. The plasma doxycycline levels had an inverse correlation with plasma rifampin levels. In the group treated with rifampin, those who were rapid acetylators had lower levels of doxycycline. In conclusion, combined treatment with rifampin reduces the levels of doxycycline in plasma. These data suggest that therapeutic failures or relapses may result from this interaction."