Classified as antibiotics, oral contraceptives or retinoids, oral acne medications treat acne from within. Oral antibiotics kill bacteria that cause acne, reducing inflammation and preventing breakouts. Oral contraceptives treat acne caused by overactive oil glands. Retinoids reduce inflammation and regulate the production and shedding of skin cells. Discuss oral acne medications with your doctor to determine how to treat your acne successfully.

Erythromycin

Erythromycin kills acne-causing bacteria to prevent new breakouts. This drug increases sun sensitivity, so avoid sunlight exposure or wear protective clothing if you have to spend time in the sun. Other side effects include diarrhea, vomiting, loss of appetite, vomiting and stomach pain.

Tetracycline

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The antibiotic tetracycline treats acne by reducing inflammation and killing the bacteria that cause acne. The most common side effects associated with this drug include nausea, vomiting, upset stomach and diarrhea.

Doxycycline

Doxycycline, a derivative of tetracycline, slows the growth of acne-causing bacteria in the body. This antibiotic increases sensitivity to sunlight, so avoid exposure to artificial ultraviolet rays or natural sunlight during your treatment. Doxycycline also reduces the effectiveness of birth control pills, according to Drugs.com, so use an alternate birth control method during treatment 4.

Minocycline

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Minocycline reduces inflammation and kills bacteria. The American Osteopathic College of Dermatology reports that this oral antibiotic kills bacteria more effectively than other acne pills. The anti-inflammatory effect of the drug leads to reduced swelling, tenderness and redness of pimples.

Clindamycin

Clindamycin suppresses the formation of bacterial proteins, resulting in fewer acne-causing bacteria. Anyone with a history of ulcerative colitis or gastroenteritis should avoid using clindamycin orally. Side effects of clindamycin include:

• peeling skin
  
• rash
  
• itching
  
• abdominal pain
  
• nausea
  
• vomiting
  
• diarrhea
  
• constipation
  
• inflammation of the esophagus

Bactrim

Bactrim contains trimethoprim and sulfamethoxazole, which both treat different types of bacterial infections. Avoid this medication if you have an allergy to any of its contents. The side effects of Bactrim include joint pain, insomnia, ringing in the ears, swollen tongue and dizziness.

Ortho Tri-Cyclen

Ortho Tri-Cyclen works to balance the hormones, which prevents the sebaceous glands from producing too much oil. Since oil clogs the pores and increases the risk of acne, this helps prevent acne breakouts. Women who smoke, and those over 35 years of age, should not take this drug due to the risk of blood clots.

Ortho-Cyclen

Ortho-Cyclen contains ethinyl estradiol and norgestimate. Doctors prescribe these hormones to treat severe acne. You should not use this drug if you have abnormal vaginal bleeding, breast or uterine cancer, history of circulation problems, liver disease, severe migraines, liver cancer or a history of blood clots.

Isotretinoin

Doctors only prescribe isotretinoin to treat nodular acne that causes severe disfigurement, according to the Mayo Clinic 1. Women who take this drug must use a reliable contraceptive method during treatment, as isotretinoin causes severe birth defects in humans. This drug helps the sebaceous glands to mature, which reduces the amount of oil produced.

Tretinoin

Tretinoin keeps the pores clear to prevent the inflammation that causes acne. This drug also helps replace older skin with new skin. Side effects of tretinoin include:

• hair loss
  
• headache
  
• indigestion
  
• itching of the skin
  
• bloating
  
• anxiety
  
• belching
  
• mood changes
  
• blurred vision
  
• nausea
  
• weakness
  
• vomiting
  
• difficulty sleeping