Questions

&Answers

about . . .

National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)

National Institutes of Health

Public Health Service • U.S. Department of Health and Human Services

Acne
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at www.niams.nih.gov.

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used to treat the health condition discussed here. When

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Table of Contents

What Is Acne? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

How Does Acne Develop? . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

What Causes Acne? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Who Gets Acne? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

How Is Acne Treated? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Treatment for Blackheads, Whiteheads, and Mild

Inflammatory Acne . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Treatment for Moderate to Severe Inflammatory Acne . . . . 8

Treatment for Severe Nodular or Cystic Acne . . . . . . . . . . 11

Treatments for Hormonally Influenced Acne 

in Women . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Other Treatments for Acne . . . . . . . . . . . . . . . . . . . . . . . . . . 14

How Should People With Acne Care for Their Skin? . . . . 14

What Research Is Being Done on Acne? . . . . . . . . . . . . . . . 16

Where Can People Find More Information 

About Acne? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Acne
Information Boxes

Normal Pilosebaceous Unit . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Types of Lesions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
This booklet contains general information about acne. It

describes what acne is and how it develops, the causes of

acne, and the treatment options for various forms of acne.

Information is also provided on caring for the skin. If you

have further questions after reading this booklet, you may

wish to discuss them with your doctor.

What Is Acne?

Acne is a disorder resulting from the action of hormones and

other substances on the skin’s oil glands (sebaceous glands)

and hair follicles. These factors lead to plugged pores and

outbreaks of lesions commonly called pimples or zits. Acne

lesions usually occur on the face, neck, back, chest, and

shoulders. Although acne is usually not a serious health

threat, it can be a source of significant emotional distress.

Severe acne can lead to permanent scarring.

How Does Acne Develop?

Doctors describe acne as a disease of the pilosebaceous units

(PSUs). Found over most of the body, PSUs consist of a

sebaceous gland connected to a canal, called a follicle, that

contains a fine hair (see “Normal Pilosebaceous Unit”

diagram). These units are most numerous on the face,

upper back, and chest. The sebaceous glands make an oily

substance called sebum that normally empties onto the skin

surface through the opening of the follicle, commonly called

a pore. Cells called keratinocytes line the follicle.

Acne

1
The hair, sebum, and keratinocytes that fill the narrow

follicle may produce a plug, which is an early sign of acne.

The plug prevents sebum from reaching the surface of the

skin through a pore. The mixture of oil and cells allows bacteria Propionibacterium acnes (P. acnes) that normally live on

the skin to grow in the plugged follicles. These bacteria produce chemicals and enzymes and attract white blood cells

that cause inflammation. (Inflammation is a characteristic

reaction of tissues to disease or injury and is marked by four

signs: swelling, redness, heat, and pain.) When the wall of

the plugged follicle breaks down, it spills everything into the

nearby skin – sebum, shed skin cells, and bacteria – leading

to lesions or pimples.

2

Normal Pilosebaceous Unit
People with acne frequently have a variety of lesions, some

of which are shown in the diagrams below. The basic acne

lesion, called the comedo (KOM-e-do), is simply an enlarged

and plugged hair follicle. If the plugged follicle, or comedo,

stays beneath the skin, it is called a closed comedo and produces a white bump called a whitehead. A comedo that

reaches the surface of the skin and opens up is called an open

comedo or blackhead because it looks black on the skin’s surface. This black discoloration is due to changes in sebum as it

is exposed to air. It is not due to dirt. Both whiteheads and

blackheads may stay in the skin for a long time.

Acne

3

Types of Lesions
Other troublesome acne lesions can develop, including the

following: 

• Papules – inflamed lesions that usually appear as

small, pink bumps on the skin and can be tender

to the touch

• Pustules (pimples) – papules topped by white or

yellow pus-filled lesions that may be red at the base 

• Nodules – large, painful, solid lesions that are lodged

deep within the skin

• Cysts – deep, painful, pus-filled lesions that can

cause scarring. 

What Causes Acne?

The exact cause of acne is unknown, but doctors believe it

results from several related factors. One important factor

is an increase in hormones called androgens (male sex

hormones). These increase in both boys and girls during

puberty and cause the sebaceous glands to enlarge and make

more sebum. Hormonal changes related to pregnancy or

starting or stopping birth control pills can also cause acne.

Another factor is heredity or genetics. Researchers believe

that the tendency to develop acne can be inherited from parents. For example, studies have shown that many school-age

boys with acne have a family history of the disorder. Certain

drugs, including androgens and lithium, are known to cause

acne. Greasy cosmetics may alter the cells of the follicles and

make them stick together, producing a plug.

4
Acne

5

Factors That Can Make Acne Worse

Factors that can cause an acne flare include: 

• Changing hormone levels in adolescent girls and

adult women 2 to 7 days before their menstrual

period starts

• Oil from skin products (moisturizers or cosmetics)

or grease encountered in the work environment

(for example, a kitchen with fry vats) 

• Pressure from sports helmets or equipment, backpacks, tight collars, or tight sports uniforms 

• Environmental irritants, such as pollution and high

humidity

• Squeezing or picking at blemishes

• Hard scrubbing of the skin

• Stress.

Myths About the Causes of Acne

There are many myths about what causes acne. Chocolate

and greasy foods are often blamed, but there is little evidence

that foods have much effect on the development and course

of acne in most people. Another common myth is that dirty

skin causes acne; however, blackheads and other acne lesions

are not caused by dirt. Stress doesn’t cause acne, but research

suggests that for people who have acne, stress can make it

worse.
Who Gets Acne?

People of all races and ages get acne. It is most common in

adolescents and young adults. An estimated 80 percent of all

people between the ages of 11 and 30 have acne outbreaks at

some point. For most people, acne tends to go away by the

time they reach their thirties; however, some people in their

forties and fifties continue to have this skin problem.

How Is Acne Treated?

Acne is often treated by dermatologists (doctors who specialize in skin problems). These doctors treat all kinds of acne,

particularly severe cases. Doctors who are general or family

practitioners, pediatricians, or internists may treat patients

with milder cases of acne.

The goals of treatment are to heal existing lesions, stop new

lesions from forming, prevent scarring, and minimize the

psychological stress and embarrassment caused by this disease. Drug treatment1 is aimed at reducing several problems

that play a part in causing acne: 

• abnormal clumping of cells in the follicles

• increased oil production

• bacteria

• inflammation. 

1 All medicines can have side effects. Some medicines and side effects are mentioned in

this booklet. Some side effects may be more severe than others. You should review the

package insert that comes with your medicine and ask your health care provider or

pharmacist if you have any questions about the possible side effects.

6
Depending on the extent of the problem, the doctor may recommend one of several over-the-counter (OTC) medicines

and/or prescription medicines. Some of these medicines

may be topical (applied to the skin), and others may be

oral (taken by mouth). The doctor may suggest using more

than one topical medicine or combining oral and topical

medicines.

Treatment for Blackheads, Whiteheads, and

Mild Inflammatory Acne

Doctors usually recommend an OTC or prescription topical

medicine for people with mild signs of acne. Topical medicine is applied directly to the acne lesions or to the entire

area of affected skin. 

There are several OTC topical medicines used for mild

acne. Each works a little differently. Following are the

most common ones:

• Benzoyl peroxide – destroys P. acnes, and may also

reduce oil production

• Resorcinol – can help break down blackheads and

whiteheads

• Salicylic acid – helps break down blackheads and

whiteheads. Also helps cut down the shedding of

cells lining the hair follicles

• Sulfur – helps break down blackheads and

whiteheads.

Acne

7
Topical OTC medicines are available in many forms, such as

gels, lotions, creams, soaps, or pads. In some people, OTC

acne medicines may cause side effects such as skin irritation,

burning, or redness, which often get better or go away with

continued use of the medicine. If you experience severe or

prolonged side effects, you should report them to your doctor.

OTC topical medicines are somewhat effective in treating

acne when used regularly; however, it may take up to 8

weeks before you see noticeable improvement.

Treatment for Moderate to Severe

Inflammatory Acne

People with moderate to severe inflammatory acne may be

treated with prescription topical or oral medicines, alone or

in combination. 

Prescription Topical Medicines

Several types of prescription topical medicines are used to

treat acne. They include:

• Antibiotics – help stop or slow the growth of bacteria

and reduce inflammation 

• Vitamin A derivatives (retinoids) – unplug existing

comedones (plural of comedo), allowing other

topical medicines, such as antibiotics, to enter the

follicles. Some may also help decrease the formation

8
of comedones. These drugs contain an altered form

of vitamin A. Some examples are tretinoin (Retin-A2

),

adapalene (Differin), and tazarotene (Tazorac)

• Others – may destroy P. acnes and reduce oil production or help stop or slow the growth of bacteria and

reduce inflammation. Some examples are prescription

strength Benzoyl peroxide, sodium sulfacetamide/

sulfur-containing products, or Azelaic acid (Azelex).

Like OTC topical medicines, prescription topical medicines

come as creams, lotions, solutions, gels, or pads. Your doctor

will consider your skin type when prescribing a product.

Creams and lotions provide moisture and tend to be good

choices for people with sensitive skin. If you have very oily

skin or live in a hot, humid climate, you may prefer an

alcohol-based gel or solution, which tends to dry the skin.

Your doctor will tell you how to apply the medicine and

how often to use it.

For some people, prescription topical medicines cause minor

side effects, including stinging, burning, redness, peeling,

scaling, or discoloration of the skin. With some medicines,

such as tretinoin, these side effects usually decrease or go

away after the medicine is used for a period of time. If side

effects are severe or don’t go away, notify your doctor.

2 Brand names included in this booklet are provided as examples only, and their

inclusion does not mean that these products are endorsed by the National Institutes

of Health or any other Government agency. Also, if a particular brand name is not

mentioned, this does not mean or imply that the product is unsatisfactory.

Acne

9
As with OTC medicines, the benefits of prescription topical

medicines are not immediate. Your skin may seem worse

before it gets better. It may take from 4 to 8 weeks to notice

improvement.

Prescription Oral Medicines

For patients with moderate to severe acne, doctors often prescribe oral antibiotics. Oral antibiotics are thought to help

control acne by curbing the growth of bacteria and reducing

inflammation. Prescription oral and topical medicines may

be combined. Common antibiotics used to treat acne are

tetracycline (Achromycin V), minocycline (Dynacin,

Minocin), and doxycycline (Adoxa, Doryx, and Monodox).

Other oral medicines less commonly used are clindamycin

(Cleocin), erythromycin, or sulfonamides (Bactrim). Some

people taking these antibiotics have side effects, such as an

upset stomach, dizziness or lightheadedness, changes in

skin color, and increased tendency to sunburn. Because

tetracyclines may affect tooth and bone formation in fetuses

and young children, these drugs are not given to pregnant

women or children under age 14. There is some concern,

although it has not been proven, that tetracycline and

minocycline may decrease the effectiveness of birth control

pills. Therefore, a backup or another form of birth control

may be needed. Prolonged treatment with oral antibiotics

may be necessary to achieve the desired results.

10
Treatment for Severe Nodular or Cystic Acne

People with nodules or cysts should be treated by a dermatologist. For patients with severe inflammatory acne that does

not improve with medicines such as those described above,

a doctor may prescribe isotretinoin (Accutane), a retinoid

(vitamin A derivative). Isotretinoin is an oral drug that is

usually taken once or twice a day with food for 15 to 20

weeks. It markedly reduces the size of the oil glands so that

much less oil is produced. As a result, the growth of bacteria

is decreased.

Advantages of Isotretinoin (Accutane)

Isotretinoin is a very effective medicine that can help prevent

scarring. After 15 to 20 weeks of treatment with isotretinoin,

acne completely or almost completely goes away in most

patients. In those patients where acne recurs after a course

of isotretinoin, the doctor may institute another course of

the same treatment or prescribe other medicines.

Disadvantages of Isotretinoin (Accutane)

Isotretinoin can cause birth defects in the developing fetus

of a pregnant woman. It is important that women of childbearing age are not pregnant and do not get pregnant

while taking this medicine. Women must use two separate

effective forms of birth control at the same time for 1 month

before treatment begins, during the entire course of treatment,

and for 1 full month after stopping the drug. You should ask

your doctor when it is safe to get pregnant after you have

stopped taking isotretinoin.

Acne

11
Some people with acne become depressed by the changes

in the appearance of their skin. Changes in mood may be

intensified during treatment or soon after completing a

course of medicines like isotretinoin. There have been a

number of reported suicides and suicide attempts in

people taking isotretinoin; however, the connection

between isotretinoin and suicide or depression is not known.

Nevertheless, if you or someone you know feels unusually

sad or has other symptoms of depression, such as loss of

appetite, loss of interest in once-loved activities, or trouble

concentrating, it’s important to consult your doctor.

Other possible side effects of isotretinoin include:

• dry eyes, mouth, lips, nose, or skin (very common)

• itching

• nosebleeds

• muscle aches

• sensitivity to the sun

• poor night vision

• changes in the blood, such as an increase in fats in the

blood (triglycerides and cholesterol)

• change in liver function.

To be able to determine if isotretinoin should be stopped if

side effects occur, your doctor may test your blood before you

start treatment and periodically during treatment. Side

effects usually go away after the medicine is stopped.

12
Treatments for Hormonally Influenced Acne

in Women

In some women, acne is caused by an excess of androgen

(male) hormones. Clues that this may be the case include

hirsutism (excessive growth of hair on the face or body),

premenstrual acne flares, irregular menstrual cycles, and

elevated blood levels of certain androgens. 

The doctor may prescribe one of several drugs to treat

women with this type of acne:

• Birth control pills – to help suppress the androgen

produced by the ovaries 

• Low-dose corticosteroid drugs, such as prednisone

(Deltasone) or dexamethasone (Decadron,

Hexadrol) – to help suppress the androgen

produced by the adrenal glands

• Antiandrogen drugs such as spironolactone

(Aldactone) – to reduce the excessive oil production. 

Side effects of antiandrogen drugs may include irregular

menstruation, tender breasts, headaches, and fatigue.

Acne

13
Other Treatments for Acne

Doctors may use other types of procedures in addition to

drug therapy to treat patients with acne. For example, the

doctor may remove the patient’s comedones during office

visits. Sometimes the doctor will inject corticosteroids

directly into lesions to help reduce the size and pain of

inflamed cysts and nodules. 

Early treatment is the best way to prevent acne scars. Once

scarring has occurred, the doctor may suggest a medical or

surgical procedure to help reduce the scars. A superficial laser

may be used to treat irregular scars. Dermabrasion (or microdermabrasion), which is a form of “sanding down” scars, is

sometimes used. Another treatment option for deep scars

caused by cystic acne is the transfer of fat from another part

of the body to the scar. A doctor may also inject a synthetic

filling material under the scar to improve its appearance.

How Should People With Acne Care for Their Skin?

Clean Skin Gently

If you have acne, you should gently wash your face with a

mild cleanser, once in the morning and once in the evening,

as well as after heavy exercise. Wash your face from under the

jaw to the hairline and be sure to thoroughly rinse your skin. 

Ask your doctor or another health professional for advice on

the best type of cleanser to use.

14
Using strong soaps or rough scrub pads is not helpful and

can actually make the problem worse. Astringents are not

recommended unless the skin is very oily, and then they

should be used only on oily spots. 

It is also important to shampoo your hair regularly. If you

have oily hair, you may want to wash it every day.

Avoid Frequent Handling of the Skin 

Avoid rubbing and touching skin lesions. Squeezing, pinching or picking blemishes can lead to the development of scars

or dark blotches. 

Shave Carefully 

Men who shave and who have acne should test both electric

and safety razors to see which is more comfortable. When

using a safety razor, make sure the blade is sharp and soften

your beard thoroughly with soap and water before applying

shaving cream. Shave gently and only when necessary to

reduce the risk of nicking blemishes.

Avoid a Sunburn or Suntan

Many of the medicines used to treat acne can make you more

prone to sunburn. A sunburn that reddens the skin or suntan

that darkens the skin may make blemishes less visible and

make the skin feel drier. However, these benefits are only

temporary, and there are known risks of excessive sun exposure, such as more rapid skin aging and a risk of developing

skin cancer. 

Acne

15
Choose Cosmetics Carefully 

While undergoing acne treatment, you may need to change

some of the cosmetics you use. All cosmetics, such as foundation, blush, eye shadow, moisturizers, and hair-care products

should be oil free. Choose products labeled noncomedogenic

(meaning they don’t promote the formation of closed pores).

In some people, however, even these products may make

acne worse.

For the first few weeks of treatment, applying foundation evenly

may be difficult because the skin may be red or scaly, particularly with the use of topical tretinoin or benzoyl peroxide.

What Research Is Being Done on Acne?

Medical researchers are working on new drugs to treat acne,

particularly topical antibiotics to replace some of those in

current use. As with many other types of bacterial infections,

doctors are finding that, over time, the bacteria that are associated with acne are becoming resistant to treatment with

certain antibiotics, though it is not clear how significant a

problem this resistance represents.

Scientists are also trying to better understand the mechanisms involved in acne so that they can develop new treatments that work on those mechanisms. For example, one

group of NIAMS-supported researchers is studying the

mechanisms that regulate sebum production in order to

identify ways to effectively reduce its production without the

side effects of current medicines. Another group is trying to

16
Acne

17

understand how P. acnes activates the immune system in

order to identify possible immunologic interventions. Other

areas of research involve examining the effects of isotretinoin

on an area of the brain that might lead to depression and

developing a laser system to treat acne and acne-related scars

without damaging the outer layers of the skin. 

Researchers in Germany, funded by German institutions,

have taken P. acnes and identified its genetic information

(genome). This information may help researchers develop

new treatments to target the bacteria.

Where Can People Find More Information About Acne?

■ National Institute of Arthritis and Musculoskeletal

and Skin Diseases (NIAMS)

National Institutes of Health 

1 AMS Circle

Bethesda, MD 20892–3675

Phone: 301–495–4484 or 

877–22–NIAMS (226–4267) (free of charge)

TTY: 301–565–2966 

Fax: 301–718–6366

E-mail: NIAMSInfo@mail.nih.gov

www.niams.nih.gov

NIAMS provides information about various forms of

arthritis and rheumatic disease and bone, muscle, joint,

and skin diseases. It distributes patient and professional

education materials and refers people to other sources of

information. Additional information and updates can

also be found on the NIAMS Web site.
18

■ American Academy of Dermatology

P.O. Box 4014 

Schaumburg, IL 60168–4014 

Phone: 847–330–0230 or 

888–462–3376 (free of charge) 

Fax: 847–330–0050 

www.aad.org

This national organization can provide referrals to

dermatologists. It also publishes a brochure on acne

for adults and a fact sheet for young people. These

are available on the organization’s Web site or can be

obtained by calling or writing to the academy. 

Acknowledgments

NIAMS gratefully acknowledges the assistance of Laurence H. Miller, M.D.,

Chevy Chase, MD; Kenneth A. Katz, M.D., M.Sc., University of Pennsylvania

School of Medicine, Philadelphia; Edward W. Cowen, M.D., National Cancer

Institute, NIH; and Alan Moshell, M.D., NIAMS, NIH, in the preparation and

review of this booklet.
The mission of the National Institute of Arthritis and

Musculoskeletal and Skin Diseases (NIAMS), a part of the

Department of Health and Human Services’ National Institutes of Health (NIH), is to support research into the causes,

treatment, and prevention of arthritis and musculoskeletal and

skin diseases; the training of basic and clinical scientists to

carry out this research; and the dissemination of information

on research progress in these diseases. The National Institute

of Arthritis and Musculoskeletal and Skin Diseases Information Clearinghouse is a public service sponsored by the

NIAMS that provides health information and information

sources. Additional information can be found on the NIAMS

Web site at www.niams.nih.gov.
U.S. Department of Health and Human Services

Public Health Service

National Institutes of Health

National Institute of Arthritis and 

Musculoskeletal and Skin Diseases

NIH Publication No. 06–4998

January 2006