Helping People Achieve Clear Skin Since 2007

Helping People Achieve Clear Skin Since 2007

Ampicillin, Antibiotics, and the Treatment of Acne

By Dr. Jaggi Rao, MD, FRCPC, Double board-certified dermatologist

Should you ask your doctor to write a prescription for ampicillin for acne? Or, if you live in a country where you can buy antibiotics over the counter without seeing a doctor, should you use ampicillin to fight acne nodules, cysts, and pimples?

Antibiotics and acne
Ampicillin used to be prescribed for treating acne, but because of antibiotic resistance, other treatments would be a better choice.


  • Ampicillin used to be used for treating acne, but acne bacteria have been resistant to it since the early 1980s.
  • Ampicillin is still used for treating impetigo, gonorrhea, and E. coli infections.
  • It is possible to have both acne and a skin condition called impetigo. Treatments for impetigo won’t clear up acne, and treatments for acne don’t have any effect on impetigo.
  • Ampicillin can be very useful for non-acne skin infections when there is an allergy to Neosporin.
  • Ampicillin has to be taken at least four times per day. It can cause serious side effects.
  • The skin care you do with a complete acne care system like Exposed Skin Care can also minimize your need for ampicillin to treat other skin conditions.

The Futility of Treating Acne with Ampicillin

The simple fact is that acne is constantly outsmarting the makers of antibiotics. The way the acne bacterium Propionibacterium acnes causes pimples to break out is not by any direct attack on the skin. Instead, acne bacteria release what are known as chemotactic factors to redirect the immune system’s attack on them to neighboring healthy skin cells. Acne bacteria release these factors in pores as a kind of signal to neutrophils from the immune system to attack. But because these chemotactic factors are attached to skin cells, the immune system kills skin instead of bacteria.

To cure acne, it is not enough to kill acne bacteria. It is also necessary to stop the effects of chemotactic factors. When ampicillin was first made available in 1961, it could both kill acne bacteria and stop the inflammation they cause. By 1981, however, so many acne bacteria had developed resistance to ampicillin that it no longer either killed the bacteria or reduced inflammation. Thirty years later, in 2011, ampicillin is even less effective against acne.

If Ampicillin Isn’t Good For Acne, Is It Any Use at All?

Even though ampicillin does not treat acne, it is still very useful for treating other kinds of skin infections. Ampicillin continues to be used with success to treat staph and strep infections of the skin.

Staph infections cause bumps that look like especially inflamed pimples. These bumps get their start in tiny cracks or cuts in the skin, not in pores. The reason they are often much more painful than acne is that while acne bacteria redirect inflammation generated by the immune system to surrounding skin, staph bacteria can release their own toxins into the skin.

Acne infections are mostly limited to the face. Staph infections can break out anywhere on the body, but especially the fingers and toes. They can cause the blood to clot so that they escape the immune system, and they can travel throughout the body causing tissue destruction. Clear, yellow pus leaking from a sore on the skin is a telltale sign of a staph infection.

Strep infections can occur anywhere on the body, but they are most common on the face in adults and on the buttocks in children. Strep infections literally dissolve the skin, but usually only the uppermost layers of the skin. The skin blisters and releases a thin, honey-like fluid that dries hard on the skin.

Both staph and strep bacteria can cause a condition called impetigo. When impetigo is caused by staph infection, it usually begins as a sinus infection. Mucus falls on broken skin, and staph bacteria make the skin blister. Because the staph infection goes deep into the skin, these blisters burst very slowly, deflating from the middle to the sides. Staph infections can cause permanent swelling of nearby lymph nodes and also scar the skin.

When strep bacteria cause impetigo, they don’t go as deep into the skin. Blisters burst faster. They almost never cause scarring and they don’t cause swollen lymph nodes. This form of strep, however, is much more contagious.

There is a product called Neosporin that treats both kinds of impetigo. Neosporin is a combination of  bacitracin, neomycin, and polymyxin B. None of these antibiotics have any effect on acne bacteria, but together, they are very useful for treating impetigo—unless the user is allergic to one or more of the three components of the treatment.

That’s where ampicillin is very useful. People who can’t use Neosporin usually can use ampicillin. Other antibiotics, especially clindamycin, are needed for treating acne bacteria, but ampicillin treats other disfiguring infections of the skin.

Do People Who Have Acne Ever Need Ampicillin?

If you are treating pimples with benzoyl peroxide and they don’t get better, your doctor may suspect (or, chances are, run a culture to test for) staph or strep infections of the skin. Ampicillin won’t do anything for acne, but it may help a great deal with other skin infections.

Ampicillin is given in capsules, in a liquid form that your drink, or by injection. One downside of ampicillin is that it has to be taken at least four times a day. The liver breaks down 50% of the ampicillin in the bloodstream every 90 minutes.

Another downside of ampicillin is that it often has serious side effects. This antibiotic can cause rashes, exfoliative (“peeling”) dermatitis, and reductions in red and white blood cell counts. It is also known to cause a condition called “hairy tongue,” which is due to a yeast infection of the mouth, and yeast infections in the urinary tract. It can cause inflammation of the mouth and a bruise-like condition known as thrombocytopenic purpura.

Using both ampicillin and certain other antibiotics at the same time can cause fatal anaphylactic reactions. Ampicillin must never be combined with demeclocycline, doxycycline, minocycline, or tetracycline. Three of these four antibiotics are often prescribed for acne. It can also interact with aluminum hydroxide from deodorants, vitamin C, aspirin, estrogen, antidepressants, and most modern antibiotics.

Ampicillin really is not something you want to take on your own. There are just too many possibilities for treatment to go horribly wrong. If you use ampicillin, you should use it under a doctor’s care.

You may be able to avoid the need for staph and strep treatments if you do the regular cleansing of your skin required to keep acne in check. One of the best ways to keep acne and other skin problems under control is with a complete treatment system such as Exposed Skin Care.

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