Tetracycline derivative medications include:

• Demeclocycline (Declomycin)
• Doxycycline (Adoxa, Adoxa TT, Doryx Oral, Doxy 100, Monodox, Oraxyl, Oracea, Periostat, Uracil, Vibra-Tabs, and Vibramycin)
• Minocycline (Dynacin, Myrac, Minocin, Minocin IV, and Solodyn)
• Tetracycline (Achromycin [DSC], Brodspec, EmTet, Sumycin Oral, TetraCap, and Topicycline Topical)

Vitamin K

Taking tetracycline derivatives may deplete vitamin K.

The major symptom of vitamin K deficiency is that your blood does not clot as it should. Low levels of vitamin K may cause:

• Easy bruising
• Bleeding even on minor injury
• Bleeding gums
• Nosebleeds
• Women may have heavy periods

Lack of vitamin K may also cause internal bleeding. This can be life threatening.

Good Bacteria

There are many types of good bacteria that live in your intestine. They help keep your digestive system healthy. Two of these bacteria are Lactobacillus acidophilus and Bifidobacterium bifidum.

Good bacteria help you to:

• Fight against infections and diseases
• Digest food

Use of some medicines may deplete good bacteria. If you do not have enough probiotics in your gut, you may have:

• Gas
• Stomach problems
• Diarrhea
• More serious infections in your intestine
• Increased risk of allergies

Some foods called probiotics contain good bacteria, and can help return your gut to normal.

The information presented here covers some of the nutrients that may be affected when you take certain medicines. If you have any of these signs and symptoms, it does not always mean you have low levels of these nutrients.

Factors that affect the level of nutrients are:

• Your medical history
• Diet
• Lifestyle
• How long you have been taking the medicine

Please talk to your health care provider. They can best address your health care needs and see if you are at risk for low levels of any nutrients.

Asiedu DK. Vitamin deficiency (Hypovitaminosis). In: Ferri FF, ed. Ferri's Clinical Advisor 2017. Philadelphia, PA: Elsevier; 2017:1359-1360.

Gold Standard Drug Database: Drug Monograph: Demeclocycline, 2016. www.clinicalkey.com/#!/content/drug_monograph/6-s2.0-171. Accessed July7, 2016.

Gold Standard Drug Database: Drug Monograph: Doxycycline, 2016. www.clinicalkey.com/#!/content/drug_monograph/6-s2.0-212. Accessed July7, 2016.

Gold Standard Drug Database: Drug Monograph: Minocycline, 2016. www.clinicalkey.com/#!/content/drug_monograph/6-s2.0-407. Accessed July7, 2016.

Gold Standard Drug Database: Drug Monograph: Tetracycline, 2016. www.clinicalkey.com/#!/content/drug_monograph/6-s2.0-598. Accessed July7, 2016.

Greenbaum LA. Vitamin K deficiency. In: Kliegman RM, Stanton BF, St Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics. 20th ed. Philadelphia, PA: Elsevier; 2016:chap 53.

James WD, Berger TG, Elston DM. Nutritional diseases. In: James WD, Berger TG, Elston DM, eds. Andrews' Diseases of the Skin. 12th ed. Philadelphia, PA: Elsevier; 2016:chap 22.

Shenkin A, Roberts NB. Vitamins and trace elements. In: Burtis CA, Ashwood ER, Bruns DE, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 5th ed. St. Louis, MO: Elsevier Saunders; 2012:chap 31.