This is a product of legendary status. It has such a cult following that you'd be hard pressed to find someone who has this and isn't head over heels in love with it.
I am one of those people. It took me a long time to finally try this, but I'm beyond glad I did. Biologique Recherche Lotion P50 1970 is classified as a "balancing exfoliator" that is to be used during the toning phase.
Description (Taken from Biologique-Recherche.com):
The P50, P50V and P50W balancing exfoliators are the unique fruit of 30 years of reflection and experience. P50 balancing exfoliators speed up the epidermis' natural exfoliating process and the reconstruction of the epidermal shield. The fortified epidermis can then fulfill its protective functions completely, enhancing skin's self-regeneration potential. Lotion P50, our most famous and coveted product, is the keystone to Biologique Recherche skin care treatment. All Biologique Recherche skin care treatments, whether administered at home or in a beauty institute, start with the P50 ritual"". It is applied in the morning and in the evening. It gently exfoliates the skin, regulates excessive sebum secretion, moisturizes and helps maintain the epidermis' acid pH. It prevents and treats in-growing hairs, and is therefore ideal for pre and post shaving skin care."
The 1970 version is the original formula that's not available in the EU, due to the phenol.
It's liquid, pungent, and highly effective. The smell is certainly phenol and vinegar together. It's very hard to describe exactly what this smells like, but it's not a scent you'll soon forget. It's chemical-y, acidic, and it lingers. P50 users can pick up the scent from a mile away.
Let's talk about the phenol. Skin and Tonics did an absolutely phenomenal post on the different versions of P50, and it's definitely a great read. Kerry explained a bit about the history of phenol, including its controversial status. Essential, phenol is used in this context as a slight numbing, acidic agent - but it may also be used as a skin lightener in other context. Caroline Hirons explained that Biologique Recherché uses P50 to prep the skin before skin treatment. Biologique Recherché themselves classify this in the "Initialization Stage" prior to the "Treatment Stage."
Your skin is definitely numbed afterwards. I wasn't totally expecting that sensation on my skin, because I wasn't fully aware that P50 1970 did in fact numb the skin. But it does.
Personally, I'm not too worried about the phenol. I don't think the concentration in P50 - even with long term use - is enough to cause any harm to the skin or body. This is my opinion, however. If you're worried about it, Biologique Recherché offer a number of versions of P50 that you can pick from that provide a similar exfoliating benefit.
The main exfoliant in P50 is lactic acid. Personally, lactic acid is far and away my favorite AHA. It's mild, effective, anti-bacterial, and can serve as a humectant as well. With that said, the lactic acid in P50 is quite strong. I've never gotten a bad reaction from using it, but your skin is definitely exfoliated effectively. You will go a bit red upon initial application, but that redness should subside. Should. I can only use this a few times a week, with incredibly mild exfoliation done in between, if at all. I prefer to use this during the evening, but then I only use AHA products in the evening due to their ability to cause sun-sensitivity.
The exfoliation will provide immediate smoothness, brightness, and glow. Your pores may look a bit smaller, congestion a bit less dull, and texture a lot less noticeable. Your products will absorb a lot more effectively, but that's a benefit of any liquid exfoliant.
Long term, P50 will definitely benefit the skin. Niacinamide is helpful at decreasing the appearance of the pores, fading discoloration, and strengthening the skin's lipid barrier. The lactic acid will encourage new collagen growth, which means a reduction in the appearance of shallow fine lines and mild loss of firmness.
This is one of those products that I'll constantly repurchase. It works. Plain and simple. I can get over the smell because I know the benefits my skin will see far surpass an element of scent.
PS: I buy mine from Rescue Spa. I enjoyed my experience shopping with them, and they provided some BR samples and a handwritten note. Talk about customer experience!
Ingredients: Water (Aqua), Glycerin, Phenol, Niacinamide, Vinegar (Acetum), Ethoxydiglycol, Magnesium Chloride, Lactic Acid, Arctium Lappa Root (Burdock Root) Extract, Salicylic Acid, Sodium Benzoate, Sulfur.
This gets a lot of hype. It's worth the hype. It smells like embalming fluid (and kind of is), but the glow and smoothes you get immediately after application make it far and away a worthwhile treatment. You can't claim you know acid toning until you've used P50!
Biologique Recherche Lotion P50 1970 $62 for 5.1 fl oz I buy mine from Rescue Spa