How Acne Is Diagnosed

In This Article

Acne is a very common skin condition and most people recognize the symptoms. But there is a wide range of severity, and different grades of acne usually require different types of treatments. It's not just the severity that varies, however, and there are several non-acne skin conditions which can be confused with the diagnosis.

Self Checks

Most people can easily self-diagnose mild acne. Symptoms may include blackheads (comedones), whiteheads (pustules), and sometimes inflamed nodules or cysts. All of these symptoms occur due to blockage of a pore.

Mild acne often doesn't require medical consultation and can be treated at home using over-the-counter products. However, if you are unsure if what you are experiencing is acne, or if your acne seems severe, see your dermatologist.

Labs and Tests

Acne is diagnosed by a simple visual inspection by your doctor. There is no test for acne. Rarely, a doctor may take a swab or scraping of a lesion or pustule for microbiological examination or culture to rule out other sources of infection. Hormone blood tests may be ordered for women to look for conditions such as pregnancy (as some acne treatments cannot be used during pregnancy), excessive prolactin, Cushing syndrome, and high testosterone (an indicator of polycystic ovaries).

Acne Grades

When diagnosing acne, dermatologists classify it into four grades. They evaluate the types of comedones (blackheads) present, amount of inflammation present, breakout severity, how widespread the acne is and what areas of the body are affected. Grades of acne are classified as follows:

  • Grade I: The mildest form of acne is referred to as grade I. With grade I acne (mild acne) the skin will display blackheads, whiteheads or milia, and occasionally minor pimples. There is no inflammation (minimal redness, swelling, or tenderness). Grade I acne can usually be cleared with over-the-counter treatments.
  • Grade II: Grade II acne is considered moderate acne. A greater number of blackheads and whiteheads are present on the skin than with grade I. Papules and pustules (whiteheads) are more frequently found. Grade II acne may also be treated with over-the-counter products. However, if there is no improvement after six to eight weeks, consult your doctor.
  • Grade III: Grade III acne is considered moderate to severe acne. The difference between Grade II and Grade III acne is the amount of inflammation present. Papules and pustules will be more numerous and there will be a greater amount of redness and inflammation found on the skin. Nodules are often present. This type of acne should be evaluated by your dermatologist, as it can be both painful and leave behind scars.
  • Grade IV: Grade IV acne is the most severe grade of acne. With grade IV acne the skin will display many pustules, nodules, and cysts. Blackheads and whiteheads are usually numerous. There is pronounced inflammation, and breakouts likely extend to areas other than the face such as the neck, upper chest, and back. Grade IV acne, also called cystic acne, must be treated by a dermatologist.

Inflamed vs. Non-Inflamed Acne

Acne can also be divided into two classes. These include non-inflamed acne breakouts with open and closed comedones (blackheads) and inflamed acne breakouts, with papules, pustules, nodules, and/or cysts.


Imaging is not used in diagnosing acne. But if there are indications of predisposing conditions such as ovarian cysts, ovarian tumor, or adrenal tumor, the doctor may order X-rays, CT scans, or MRI studies.

Differential Diagnoses

Some skin conditions can look remarkably similar to acne, although their causes and treatments are different. If you are unsure, it is always wise to consult a dermatologist.


Rosacea is sometimes mistakenly referred to as "adult acne" but is caused by a different mechanism than acne in adults. You may need to see a dermatologist to distinguish these conditions early on. Rosacea causes red, flushed skin with papules and pustules, especially in the nose and cheek area, and may lead to the classic enlargement and bumpiness of the nose for which it is best known. It is uncommon before the age of 30 and occurs more often in fair-skinned individuals and women (though it tends to be more severe in men).


Folliculitis is a condition in which the hair follicle is inflamed and can result in bumps or pustules. It is usually caused by bacteria such as strep or staph and is treated with topical or oral antibiotics.

Keratosis Pilaris

Keratosis pilaris is a rash marked by small, rough, "goose-flesh" like bumps most often found on the upper arms, thighs, and buttocks, and sometimes the face. It commonly occurs at the same time in life when acne is prevalent, and roughly 50 percent of teens have some degree of the condition.

Miliaria Rubra

Milaria rubra is a rash characterized by small red bumps on the surface of the skin and is caused by excessive heat exposure. It is also known as heat rash or prickly heat.

Rashes Due to Certain Cancer Drugs

Some targeted therapy drugs for cancer, such as Tarceva (erlotinib) cause a rash that closely resembles acne. People who are taking these medications may frantically try using acne preparations but with no relief since the rash is due to a mechanism unrelated to that of acne. If you have a rash that looks like acne while going through cancer treatment, talk to your oncologist.

A Word From Verywell

A proper diagnosis of acne includes not only a confirmation of the classic findings but a description of the severity of the rash. Determining the severity is important in choosing the best treatment options to improve your comfort and minimize scarring. If you are coping with acne that is grade II or higher, or even if you have mild acne but it is not responding to over-the-counter medications, make sure to consult a dermatologist. Fortunately, treatment options are available for even the most severe types of acne.

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Article Sources

  • Becker, M., Wild, T., and C. Zouboulis. Objective Assessment of Acne. Clinical Dermatology. 2017. 35(2):147-155.
  • Weller, Richard P. J. B., Hamish J.A. Hunter, and Margaret W. Mann. Clinical dermatology. Chichester (West Sussex): John Wiley & Sons Inc., 2015. Print.