Thanks to an influx of direct-to-consumer subscription brands, acne treatment is getting personal.

Companies like Curology and MDacne are using online-and app-based quizzes to create personalized treatment plans and medication to treat acne to differentiate from category leaders like Neutrogena, Clean & Clear and Clearasil. At the same time, these brands are borrowing a page out of Proactiv’s controversial playbook by selling products on a subscription-only, monthly replenishing basis.

Curology, started in 2013 by dermatologist David Lortscher, walks new customers through an online quiz that asks about skin type and conditions. Additionally, consumers fill out a detailed medical history section and upload no-makeup selfies. One signature medication — that doesn’t rely on typical drugstore ingredients like salicylic acid and benzoyl peroxide — is then delivered to the patient without having to visit a doctor or stop by a pharmacy. Treatments are tweaked as the skin changes and adapts to the product.

MDAcne follows a similar quiz format and selfie upload strategy as Curology, but takes it one step further by tying it into its mobile app, which uses proprietary computer vision technology to diagnose the skin. The company started as a mobile app that recommended acne products to buy from Amazon in 2016 but relaunched in January with its own personalized product line that includes not only an FDA-cleared customized treatment cream that uses benzoyl peroxide and salicylic acid, but also a corresponding moisturizer and cleanser.

Asking customers to fill out surveys and answer quiz questions in the pursuit of a more personalized product is common practice for DTC brands looking for customer loyalty. Lingerie brands like Third Love and True&Co use fit quizzes to capture a customer’s bra size and recommend them the right products, while hair-care brand Prose seeks to mix up bespoke shampoos and conditioners based on a person’s self-reported hair type. Curology, like Prose, is backed by Forerunner Ventures, as well as Advance Vixeid Partners and Sherpa Capital.

Making dermatologist-level skin-care available to more people sparked the idea for Curology, said svp of marketing Fabian Seelbach. The Curology regimen is at a minimum a six- to eight-week treatment plan, according to Seelbach, so the company relies on an ongoing $19.95 subscription model to retain customers per month, though there is a 90-day money-back guarantee. While Seelbach wouldn’t disclose exact figures, he said that new monthly members for Curology have grown by five times in the last 12 months, and total membership has tripled in the last year.

There’s money to be made: Currently, the acne treatment category, made up of medicated creams and skin cleansers, among other products, is valued at $620.5 million, according to market research firm Euromonitor International.

MDacne co-founder and CEO Oded Harth, who started the business with his dermatologist father Yoram, said that beyond its own $29.95 per month subscription model, its “selfie tracker” feature on the app is meant to drive loyalty. The tool analyzes patients’ acne over time as a way to fuel commitment from customers. Members also receive periodic reminders from the app, as well as chat access to dermatologists.

“The No. 1 failure for acne treatments is not only the wrong product but also not using the product long enough,” said Harth. “As your skin changes and gets better, the app will re-formulate your treatment.”

Though Harth wouldn’t release total app downloads, aside from saying it is the “No. 1 acne app,” he revealed the company has analyzed and treated more than 300,000 patients through the app. Harth has four additional products in development as part of the MDacne regimen, which he think will grow the business, including a body acne treatment and acne-specific sunscreen.

The plan, enabled by the quiz- and selfie-based app, is also to move beyond acne as the company’s sole focus. “We started with acne, but we want to extend to more and more skin problems,” explained Harth.