Retinol is one of those magical skin-care ingredients [1] that you either love so much you want to sing its praises to anyone who will listen, or you can't stand — and that's usually a result of a bad reaction or using the wrong product. Retinol is the holy grail [2] for its ability to fade hyperpigmentation and skin discoloration, and even treat adult acne.

Clearly by its long list of benefits, retinol is no joke; if used incorrectly it can cause some serious skin irritation [3] and dryness. Because it's so potent, you want to make sure you find not only the right type of retinol for your specific skin type, but also the right concentration. Then, your skin needs to become "retinized" — this is the initial period where it adapts to the new ingredient, which occurs by slowly introducing it into your routine [4]. This typically starts with using it once or twice a week, and then every other day, until your skin can handle daily use.

After that beginning phase, you should be able to use your retinol without any irritation, but there are still a few usage guidelines you'll want to follow. Here are the important retinol rules to know — and how to safely break a few of them, if you're so inclined.

Retinol Rule #1: Start Low in Strength

There is no shortage of retinol products on the market, which can make finding the right one for your skin a little tricky. "The percent of the retinoid and the base in which it is compounded affects the strength of the product," board-certified dermatologist Dendy Engelman [5], MD, told POPSUGAR. For example, a retinol gel is stronger than a retinol cream. "When comparing retinoids and retinols to one another, you have to make sure that you are comparing the same molecules to one another to determine the strength."

She recommended you start with a low strength of 0.25 percent once a week and to work your way up to a stronger formula slowly, if needed. "Stronger is not always better," said Dr. Engelman. "You need to train your skin to tolerate Vitamin A and derivatives are a great way to do that."

Retinol Rule #2: Look For the Right Product Packageing

Have you ever stopped to think about the packageing of your skin-care products farther than just if they look good in a shelfie? Celebrity aesthetician Renee Rouleau [6] recommends that you do, especially when it comes to retinol. First, you want to choose a formula in opaque packageing.

"Retinol is so delicate that it deactivates quickly if the formula inside the bottle is exposed to light — even if it's encapsulated," said Rouleau. "The worst offender is a clear bottle with no box. It has likely been sitting on a shelf under lights for potentially months at a time. The light is rendering the retinol product ineffective." Another big no-no for retinol is heat so be careful not to leave this product in your car or bathroom when you shower. "Along with heat and light, oxygen is a major enemy of sensitive ingredients like retinol," said Rouleau.

The best retinol product will be in an airless container. This packageing keeps the product potent until the very last drop." Take this into consideration when shopping for a retinol product, as you want to make sure your money is going towards a formula that will stay effective, down to the last drop.

The Rule #3: Don't Over-Exfoliate While Using Retinol

Because retinol makes your skin more sensitive, you want to make sure you don't over-exfoliate or irritate your complexion. But you can use your retinol and your exfoliating products together in harmony. "Retinol is not technically an exfoliant however, in an effort to not over-irritate the skin, I do not recommend using a leave-on acid exfoliator like a serum along with retinol in the same routine," said Rouleau. "Retinol with an acid combination can be too active and you risk damageing the skin's protective barrier." This includes products formulated with glycolic or lactic acids, but that's not all.

"Avoid mixing retinol with acne treatments containing salicylic acid as they cause drying and redness as well," said Dr. Engelman. "Avoid mixing benzoyl peroxide with retinol as it has been shown that the two ingredients together have a tendency to deactivate each other." But there is an exception to this rule: if the products have been specifically formulated to be used simultaneously, then it's OK.

Starting retinol doesn't mean you have to give up AHAs and BHAs forever — it's just until your skin fully adjusts. "Over time, the skin acclimated to vitamin A derivatives like retinol and retinoids and gentle exfoliants containing AHA/BHAs can be slowly incorporated into your routine."

The Rule #4: Don't Mix Vitamin C With Retinol

If you're using retinol to fade acne scars or hyperpigmentation you may be thinking retinol and vitamin c are the perfect skin brightening mix, but that's not the case. "Retinol users should avoid vitamin C products that sting when applied to the skin," said Rouleau. "Most vitamin C products out on the market use the acid forms of the vitamin, like Ascorbic Acid." That doesn't mean you need to choose one over the other — you just need to be strategic in application [7].

Retinol should always be used at night, follow by a sunscreen in the morning. Vitamin C, on the other hand, should be used in the morning to protect against free radical damage and provide your skin with antioxidants. You never want to layer them together in the same routine.

The Rule #5: Don't Start Retinol Too Early

Yes, retinol is an amazing product, but unless you're directed to by a professional, you don't want to start using it too early. "Some patients start using retinoids earlier to combat acne issues," said Dr. Engelman. "Others I advise to start later to treat signs of ageing. Timing depends on what skin issue we are targeting."

The Rule #6: Be Careful When It Comes to Prescription Retinol

You may think that prescription products are always better, but that may not be the case for your skin. The main difference between over-the-counter (OTC) and prescription retinol is the first is a weaker form of vitamin A and therefore more forgiving on the skin. "Retinoic acid (what you find in prescription products) is the most active form of Vitamin A," said Dr. Engelman. "Biochemically, retinoid and retinol, have the same effects — it may just take longer to see results with retinols, since they are weaker."

But Rouleau only recommends using prescription retinoids if you're over 35 and your skin can handle it. "Most people have a certain degree of skin sensitivity, which is why I suggest using a non-prescription retinol first," said Rouleau. The exceptions to this are if you have certain skin concerns, they may require a more heavy-duty approach, like someone with indented facial scarring from acne or melasma.

When in doubt consult with your dermatologist to find out what's best for your skin.