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The Mechanism for Minocycline (Minocin, Dynacin, Solodyn) Associated Staining of the Teeth and How is it Different from Tetracycline


  • Unfortunately, like tetracycline, minocycline can also stain the teeth but does so through a different process that can affect all patients, not just those less than 8 years of age.
  • Minocycline induced teeth staining or discoloration appears to be multifactorial. These include an "intrinsic theory", where the drug binds to collagen in the teeth; an "extrinsic theory", where the drug etches into the enamel and is oxidized and lastly when haemosiderin (end product of minocycline) chelates with iron to form a complex in the teeth.
  • Teeth discoloration from minocycline differs from tetracycline by being blue-gray instead of brown, as seen with tetracycline.  In addition and unlike tetracycline, minocycline induced stains doe not fluoresce under UV light.

Editor-in-Chief: Anthony J. Busti, MD, PharmD, FNLA, FAHA
Jon D. Herrington, PharmD, BCPS, BCOP and Donald S. Nuzum, PharmD, BCACP, CDE
Last Reviewed: October 2015


  • Minocycline (Minocin, Dynacin, Solodyn) is a derivative of tetracycline.   Minocycline has the same basic ring structure as tetracycline, but lacks a functional group at C6 and has a substitution of a dimethylamino group at C7.1  These small modifications increase both the lipophilicity (increased lipid solubility) and the half-life of minocycline.   Unfortunately, like tetracycline, minocycline can stain the teeth; however, it is through a process that is different from that of tetracycline.  Because of the differences in mechanism of this effect, minocycline has the potential to cause this adverse effect in all patients exposed to the drug, not just those 8 years old or younger.1,2  This is important given the likelihood of longer courses of therapy with minocycline (in particular Solodyn) for the treatment of acne.  Staining of the teeth in this population may compound the negative psychological impact of their condition.1,3  

    How does minocycline cause teeth discoloration and how is it different from tetracycline?
    Minocycline's contact with the teeth occurs through a few different processes, all of which are likely to contribute to the staining of the teeth.  The first influence has been called the "intrinsic theory", which occurs upon absorption.  Minocycline is highly protein bound in the blood and appears to bind to higher collagen containing tissue (e.g., bone and teeth) as well, which results in discoloration.1,2  The second proposed influence has been called the "extrinsic theory", which occurs when the surface of the teeth come in contact with minocycline.   There is substantial contact of minocycline with the teeth as concentrations of the drug in the saliva are about 30-60% of the concentrations seen in serum.4  In addition, minocycline can attain gingival crevicular fluid concentrations 5 times greater than concentrations attained in the serum.4  The gingival crevicular fluid is found in the groove on the external surface of the tooth where the gingiva (gums) meets the enamel of the teeth (gum line).  This high concentration is thought to etch into the enamel where the minocycline gets oxidized (turn black in color) upon exposure to oxygen or bacterial activity.5-8  The other contributor to teeth discoloration is chelation of haemosiderin (a breakdown product of minocycline) with iron to form an insoluble complex within the teeth.2,9  

    Since the cause for teeth staining or discoloration is different than tetracycline, are there any other differences that are important to know?
    Yes.  One characteristic that is different from tetracycline is that minocycline induced staining does not fluoresce under UV light.  In addition, the discoloration is a distinct blue-gray band, possibly found more in the incisal and middle third of the crown as compared to tetracycline, where the brownish discoloration primarily occurs in the gingival third of the crown.1,10                                            

    Similar to tetracycline, minocycline induced staining of the teeth is more likely to occur during longer durations of therapy and when used at higher doses (especially over 100 mg per day possibly).  The overall prevalence of teeth staining has been reported to be 3-4% with tetracycline and 3-6% with minocycline.1,7  Given the growing number of indications for the long-term use of minocycline (MRSA infections, acne, etc.), this adverse drug event would be important to consider when no alternative therapy exists. 


    1. Sanchez AR, Rogers RS 3rd, Sheridan PJ.  Tetracycline and other tetracycline-derivative staining of the teeth and oral cavity.  Int J Dermatol  2004;43:709-15.         
    2. Good ML, Hussey DL.  Minocycline: stain devil?  Br J Dermatol  2003;149:237-9.         
    3. Scopp IW, Kazandjian G.  Tetracycline-induced staining of teeth.  Postgrad Med  1986;79:202-3.  
    4. Ciancio SG, Mather ML, McMullen JA.  An evaluation of minocycline in patients with periodontal disease.  J Periodontol  1980;51:530-4.               
    5. Fendrich P, Brooke RI.  An unusual case of oral pigmentation.  Oral Surg Oral Med Oral Pathol  1984;58:288-9.        
    6. Salman RA, Salman DG, Glickman RS et al. Minocycline induced pigmentation of the oral cavity.  J Oral Med  1985;40:154-7.         
    7. Berger RS, Mandel EB, Hayes TJ et al.  Minocycline staining of the oral cavity.  J Am Acad Dermatol  1989;21:1300-1.        
    8. Bowles WH, Bokmeyer TJ.  Staining of adult teeth by minocycline: binding of minocycline by specific proteins.  J Esthet Dent  1997;9:30-4.  
    9. Rosen T, Hoffman TJ.  Minocycline-induced discoloration of the permanent teeth.  J Am Acad Dermatol  1989;21:569.  
    10. Poliak SC, DiGiovanna JJ, Gross EG et al.  Minocycline-associated tooth discoloration in young adults.  JAMA  1985;254:2930-2.

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MESH Terms & Keywords

  • Tetracycline, Minocycline, Minocin, Dynacin, Solodyn, Tooth Staining, Medication Induced Teeth Discoloration, Minocycline Teeth Staining