Sometimes acne is nothing more than a simple pimple, a bit of trapped pus consisting of sebum, dead skin cells and white blood cells. But it can be more severe. Knowing which type you have is key to a proper diagnosis and treatment plan.

Professionals recommending a course of treatment will rank acne by grade.

Grade I includes milder, non-inflamed types such as blackheads, whiteheads or milia. Grade II involves a larger number of these, and frequently includes papules or pustules that are mildly inflamed.

Papules are small lesions, a change or break in the skin, that is smaller than 5 mm - about the width of a thin cigarette. They're in the form of a bump that rises above the surface. A pustule, by contrast, is pus-filled - a mixture of bacteria, white blood cells and dead skin cells.

Grade III is more severe. The papules or pustules will be red, larger and more numerous. Grade IV is the most severe level, and includes nodules and cysts. The inflammation is usually wide spread and includes more than just the face.

Acne vulgaris is the common form of mild acne. Any of the Grade I forms will fall under this heading. They can usually be treated with over the counter medications.

In more severe form acne can develop into a type known as acne congoblata. The name may sound amusing, but the condition is anything but. It's characterized by heavy inflammation and deep abscesses. The result is often scarring and other forms of serious skin damage.

Inflamed nodules will form around comedones - a general term for blackheads, whiteheads and milia. They often grow until they spontaneously discharge pus. While they do, they're painful. When they do, they're unsightly. Keliod-type scars are commonly left behind.

Another type is known as acne fulminans. Here, the nodules will often ulcerate, leading to a painful and recurrent form of acne. The person afflicted may even develop a fever or aching joints. Treatment with corticosteroids or NSAIDs (non-steroidal anti-inflammatory drugs) is usually called for. But these treat symptoms, not the underlying cause.

In still more severe forms, a person may develop nodulocystic acne. Cysts form (red bumps produced by severe inflammation), but they're of an unusual type. Sometimes they become numerous and close enough together to form a larger inflamed area. When they form small tunnels under the skin, infection can spread more readily. A treatment of antibiotics is called for, and isotretinoin (brand name: Accutane) is frequently employed.

Gram-negative folliculitis occurs when the follicles - the shaft in which hairs grow and sebum flows from the sebaceous glands - become infected. Bacteria grow inside and the body responds by dispatching white blood cells to fight the infection. The result is a deep eruption that calls for special treatment.

The type of bacteria that produces it may be resistant to normal antibiotics. In fact, the condition may have resulted from treatment of other types of acne treated with antibiotics.

Proper diagnosis of these forms of acne calls for a visit to a professional. A dermatologist's care is warranted in these cases, as it may be in other forms of severe acne.

While there are always new questions to answer, many of the factors that tend to produce acne have been well researched.

Hormones and Sebum

It's no accident that acne tends to be associated with teens. It strikes over 85% of us during those years. It's at that stage of life when hormone levels rise sharply. Androgen levels increase in both males and females.

Among other effects, those stimulate the sebaceous glands that produce sebum, the natural oil found in hair follicles. The largest increases occur in the face, back and upper chest - right where acne tends to concentrate. The result can well be an outbreak of acne.

Increased oil or sebum isn't generally a problem if it reaches the surface. It's spread around, and often washed off with alcohol or soap and water by those who take good care of their skin. Still, blackheads may form as a result of the excess oil.

Worse, pores can close, causing them to become clogged with that excess oil. That encourages the growth of whiteheads. Also, the resulting pressure can cause follicles to rupture. The bacteria have a more 'friendly' environment in which to grow. At the same time, bacteria and the white blood cells that deal with it (normally without any problem) get trapped. The result is pus and inflammation. Acne.

Stress itself doesn't produce acne, but it can make it worse by increasing hormones. It also contributes to weakening the immune system, thus leading a less effective defense against invading bacteria. But it's not a major factor.

Drugs

Certain drugs can encourage the development of acne. Barbituates and tetracycline are known to be among the culprits. Anabolic steroids are widely recognized by professional dermatologists to be a major contributor among those who take them. Forgoing these, except for specific medical purposes, helps reduce the odds.

Heredity

Genetics plays a role, as well. How large, is still not yet quantified. The area is one of active research, and therefore the exact mechanism isn't detailed. But, statistics show that acne does tend to run in families. That may be partly due to diet or other common family circumstances. But it's more a factor of inheritance.

Diet & Skin Care

This is a much more minor cause than is commonly supposed. While certain foods are themselves greasy, that doesn't translate directly into increased oil in the skin. Of course, poor eating habits often go hand in hand with poor skin care practices. And, any food that tends to increase the production of sebum (oil) or certain hormones will have an effect.

But no study suggests that the common culprits - soft drinks, chocolate and greasy cheeseburgers, among others - play a large role in producing acne.

Poor cleansing habits play some role, because bacteria that lie near the surface sometimes remain 'unmolested'. Regular use of a good cleanser can help. Take care that the skin doesn't become excessively dry, however. That causes other problems.

Also, heavy dirt or even makeup can contribute to a problem by blocking the pore, especially if they block oil ducts. But surface dirt itself isn't responsible for acne. The dark head on blackheads is the result of exposure to air, not trapped dirt.

There's little one can do about heredity, and passing through the teen years is a normal part of life. But good skin care, quick treatment at the onset of symptoms and other controllable choices will help keep acne at bay.

In very mild forms of acne, little diagnosis is required. Most people who reach their teens will readily recognize the small blackheads or white pimples surrounded by a reddened area that constitute mild acne.

But more severe forms, where nodules or cysts form, where papules or pustules have spread around the face, shoulders and chest often call for a visit to the dermatologist. These skin professionals will obtain a complete history and carefully examine the affected areas. They'll note the color, number and size of outbreaks.

The acne may consist of a field of small, white bumps called whiteheads. These will often disappear on their own. Blackheads form when the material reaches the surface, where it combines with air to form the characteristic dark color. These two are called, respectively, closed or open comedones. A good antibacterial cleanser and time may be all that's needed.

In the more severe cases, where nodules or cysts form, the patient may have other symptoms we don't commonly associate with acne, such as fever and aching joints, or even headaches and GI (gastrointestinal) distress. These indicate more serious types of acne, calling for more specialized treatments, such as prescription drugs or lasers.

When symptoms appeared, and in what order, is important. Typically, only the patient can provide that information. It's useful to keep track by keeping a log. Note what type of lesion occurred before the appearance of any pustules and when.

Along the way the dermatologist will, naturally, attempt to rule out any alternative explanations.

Certain insect bites, such as mosquito or spider bites, can temporarily resemble acne. Mosquito bite lesions, left alone, will disappear in a day or two for all but those who are allergic. Spider bites are often harmless, but some may be poisonous and lesions can spread. That calls for entirely different treatment from acne.

Rosacea is a common skin disorder that differs from acne in several respects, but still forms papules and red pustules. Keratosis pilaris produces small bumps that may resemble whiteheads. Miliaria rubra, or heat rash, produces small red bumps. All of these would call for very different treatment from acne.

Similarly, many allergies can produce skin lesions, redness and many other symptoms similar to acne. Sexually transmitted diseases are a common ailment. Sometimes they actually produce acne, but they can cause other skin problems, too. Herpes, for example, may show up as red, painful bumps on the buttocks.

Certain drugs can actually cause acne. Anabolic steroids, lithium and prednisone, are common today. Phenobarbital and tetracycline can cause acne. Dermatologists will require a complete and honest history of drug use in order to make a proper diagnosis.

Sometimes, even excess use of Vitamin B complex can cause acne. The doctor will need to know about diet, supplements and whether any over the counter medications or remedies have already been tried.

Knowing as much as possible about your own skin and the history of any outbreaks will aid proper diagnosis. That, it should go without saying, is key to any proper treatment.

When I was a teenager and well into my young adult years, I suffered from horrible acne. I spent a lot of time (and money) at the dermatologist's office, undergoing a variety of treatments, and he used to joke with me that it was taking longer for me to grow out of acne than most of his patients. No matter what I did, the treatment would only alleviate the acne somewhat, or for a short time, then it would be back with a vengeance.

Now, there are many more effective treatment options available. Understanding acne and how it can be treated is the first step in having the kind of skin you want - free of blemish.

What is acne?

Acne is a common skin disease that results when pores get blocked and bacteria form inside them. It comes in a variety of familiar forms and affects nearly everyone at some stage, particularly in their teen years. The inflamed, red bumps that sometimes form can be painful, and even painless white pimples are unsightly.

In the surface of the skin are pores, tiny openings called a hair follicle. Deeper inside the pore, near the base of the follicle, there are sebaceous glands that produce sebum, a natural type of oil. That oil helps keep the skin flexible and protected.

Hair continues to grow through the surface, while oil or sebum oozes out the side and is spread around the area. Skin cells grow and die and are sloughed off through washing, rubbing or spontaneously. But that process can be interrupted when the pores close and when bacteria form inside them. The result is acne.

The white pimples that sometimes form are usually a combination of dead skin cells, white blood cells and bacteria. The trapped pus often creates an inflamed, red area around it. The term 'pus' is an adaptation of 'pustule', a type of acne that results when the follicle wall bursts and the white blood cells rush into the area as part of a healing process.

When the tiny bumps or spots appear black they're called blackheads, naturally enough. They're a non-inflamed form of acne that come from the material having poked through the surface. Their dark color isn't the result of contact with dirt on the skin. It's a combination of dead skin cells and sebum that have oxidized. Oxygen in the air causes a chemical reaction that turns them black.

Often, however, the material doesn't break the skin, but simply pushes it up, forming a small, white bump called whiteheads. One form are known as 'milia'. Normally dead skin cells will get washed off or simply fall off the surface. But they can get trapped underneath the surface. This type of acne is common among infants, but can affect people at any age.

All these variations go by a general medical term called 'comedones', and whether that formation is open or closed is part of the clinical difference between them.

As the acne develops it can variously form what are called papules, nodules or cysts. A papule forms when the walls holding the hair follicle burst near the surface. They're small and don't contain pus. A nodule is a hardened lump under the skin, resulting from a break at the base of the follicle. A cyst is a larger, reddened bump. They're soft, but can be very painful.

Naturally, while it's helpful to know what acne is, the most important thing is to be able to treat it. In order to do that, it's necessary to know what type we have. We hope you find the information you need here to help you determine the type of acne you have and the best treatment options.