the pathogenesis of pseudotumor cerebri syndrome ( ptc ) is poorly understood , although its diagnostic criteria are well established . while most cases are idiopathic , recent data indicate that patients with severe forms of ptc may have partial venous outflow obstruction [ 24 ] , and such patients may have greater long - term morbidity . antibiotic medications such as minocycline , tetracycline , and doxycycline have also been repeatedly implicated as a causative or contributory factor in ptc [ 57 ] . some authors suggest it is a benign condition that resolves spontaneously upon discontinuing the antibiotic [ 8 , 9 ] , while others report permanent vision loss may ensue . it is possible that venous sinus thrombosis was a confounding factor regarding disease severity in some instances , as most reported cases predate reliable magnetic resonance venography ( mrv ) . here we describe two cases of minocycline - induced ptc with severe papilledema and normal mrv , indicating that minocycline alone may be associated with severe ptc without venous sinus anomalies . retrospective case analysis was performed on cases of pseudotumor cerebri seen by two of the authors ( michael x.repka , prem s. subramanian ) in their clinical practices . a specific search for nonobese patients ( bmi  25 ) with minocycline use at the time of pseudotumor cerebri diagnosis was made , and cases identified are presented below . irb approval was not required for this study by our institutional guidelines , since it involves a case series of fewer than 3 patients . a 23-year - old woman with a 4-month history of doxycycline treatment and a subsequent 3-month history of minocycline treatment for acne developed tinnitus , vomiting , phonophobia , and photophobia along with severe headaches and progressive horizontal binocular diplopia . she was otherwise healthy and took no other medications.visual acuity was 20/15 in the right eye and 20/20 in the left eye with a left relative afferent pupillary defect.humphrey visual fields revealed a triangular scotoma in her left eye ( figure 1 ) . severe bilateral papilledema was present , greater on the left than the right .   lumbar puncture demonstrated an opening pressure of 41  cm h2o with normal cerebrospinal fluid . head ct and contrast - enhanced mri were both normal and an mrv showed no venous thrombosis or stasis . the patient 's symptoms of diplopia improved 3 weeks later , but papilledema and headache persisted with worsening of visual fields . the intracranial pressure remained elevated at 33  cm h2o despite treatment with 2  g acetazolamide / day . ventriculoperitoneal shunting was performed for intracranial pressure control . a 15-year - old girl with a 6-week history of minocycline treatment for acne vulgaris developed progressive bifrontal headache with pain around the right eye , vertical binocular diplopia , nausea , neck pain , and muscle spasm . visual acuity was 20/20 - 2 in the right eye and 20/15 - 1 in the left eye . threshold visual fields revealed enlarged blind spots in both eyes , but otherwise normal findings . dilated ophthalmoscopy disclosed florid papilledema in both eyes with peripapillary hemorrhages and choroidal folds ( figure 2 ) . head ct and enhanced mri were both normal , and an mrv showed no evidence of venous thrombosis . acetazolamide treatment was prescribed , then discontinued 5 months later after resolution of the papilledema , headaches , visual field defects , and diplopia . we present 2 cases of minocycline - associated ptc in nonobese patients in whom symptoms were severe , though there were no signs of venous sinus thrombosis on mrv . in one case , papilledema and duration of ptc can never be known for sure , and it is possible that both patients had disc swelling for some time before diagnosis and thus suffered vision loss as a result . however , vision loss and papilledema in ptc found incidentally are usually mild . there is conflicting evidence in the literature regarding the prognosis of minocycline - induced ptc . in the largest published series of minocycline - treated patients , consisting of 12 patients , 6 had severe papilledema at diagnosis and 3 had residual visual field loss . kesler et al . reported 18 patients with a history of tetracycline use associated with pseudotumor cerebri and found that 6 patients had a relapsing course , while 12 patients had rapid recovery from the disease upon stopping the antibiotic agent . the authors suggested that tetracycline played only a minor role in the patients who relapsed ; however , a number of their patients were obese , in contrast to the patients we present in this report . others have stated that minocycline - induced ptc usually has minimal visual consequence and resolves rapidly upon discontinuing the medication . normalization of intracranial pressure within 1 month of stopping tetracycline has been reported as well . however , the mechanism by which tetracycline or minocycline may induce pseudotumor cerebri has not been determined . our patient in case 1 was treated with both doxycycline and then minocycline , although her symptoms did not arise until the latter drug was used . our findings suggest that minocycline alone may induce severe ptc with persistently elevated intracranial pressure , and patients with this condition may require medical and surgical treatment beyond discontinuation of the medication . we propose that minocycline - associated pseudotumor cerebri is not a benign condition and must be followed closely with aggressive interventions to prevent vision loss .
background . 
 pseudotumor cerebri is an acknowledged but unusual complication of oral minocycline use . 
 vision loss and papilledema have been described as mild and transient , and some authors suggest that treatment is not needed . 
 methods . 
 case series of 2 patients with severe papilledema and visual field loss . results . 
 severe pseudotumor cerebri developed in 2 nonobese patients taking minocycline . 
 their disease required further treatment even upon drug discontinuation because of visual field loss and papilledema . 
 conclusions . 
 minocycline - associated pseudotumor cerebri is not always a self - limited condition and may require aggressive medical or surgical management .