What Is Natural Progesterone USP & How Does It Work in the Body?

Progesterone is one of the two primary female hormones produced naturally by the ovaries and adrenal glands. Throughout your reproductive years, progesterone balances estrogen. However, during perimenopause (the transition years leading up to menopause) and postmenopause, progesterone production drops significantly—often declining much faster than estrogen.

This hormonal imbalance can lead to common complaints such as occasional hot flashes, nighttime temperature spikes, restlessness, mood swings, irritability, and skin dryness.

The Difference Between "Bioidentical USP Progesterone" and "Wild Yam Only" Creams

Many natural creams on the market list wild yam (*Dioscorea villosa*) on their labels and claim your body turns it into progesterone. Medical science has proven that the human body cannot convert wild yam extract into progesterone on its own. Wild yam contains a plant compound called *diosgenin*, which can only be transformed into progesterone through a specialized laboratory process.

Source Naturals Eternal Woman Progesterone Cream gives you both: It contains pure Natural Progesterone USP (meeting the United States Pharmacopeia standards for chemical identity and purity that matches your body's own natural hormone molecule), combined with soothing botanical wild yam extract for complementary skin nourishment.

Why Advanced Liposomal Delivery Matters for Skin Absorption

When you take oral progesterone pills, the hormone travels directly into your digestive system and liver. During this route (known in pharmacology as "first-pass metabolism"), the liver filters out up to 85% to 90% of the active hormone before it reaches the bloodstream, creating unwanted metabolites that can cause excessive daytime drowsiness.

Source Naturals Progesterone Cream bypasses the liver by applying the hormone transdermally (through the skin). To ensure optimal absorption, Source Naturals uses an advanced liposomal delivery system:

✓ Microscopic Phospholipid Spheres

Liposomes are microscopic bubbles made of natural phospholipids (the same material that makes up your body's cell membranes). These spheres encapsulate the progesterone molecules, protecting them and allowing them to glide smoothly through the lipid-rich outer layers of your skin.

✓ Steady, Sustained Release

Because progesterone is fat-soluble (lipophilic), it collects naturally in the sub-dermal fatty tissue beneath the skin. From there, it releases slowly and steadily into the local circulation, preventing the sharp hormonal spikes and crashes associated with oral tablets.

✓ Non-Greasy, Botanical Base

Infused with jojoba oil, squalene, and aloe vera, the cream absorbs within minutes without leaving a sticky or greasy residue on your skin or clothing.

What Does Medical Research Say About Transdermal Progesterone?

In accordance with transparent health communication standards, we review what peer-reviewed scientific literature has discovered regarding over-the-counter transdermal progesterone cream:

1. Vasomotor Symptom & Hot Flash Relief

In a randomized, double-blind, placebo-controlled study published in Obstetrics & Gynecology, researchers evaluated women applying topical progesterone cream over one year. The study revealed that 83% of women in the progesterone group experienced significant improvement or complete resolution of hot flashes, compared to just 19% in the placebo group.

2. Transdermal Drug Exposure & Skin Penetration

A clinical pharmacology study published in the Journal of Clinical Pharmacology confirmed that over-the-counter progesterone creams containing ~40 mg daily resulted in measurable, steady circulating hormone levels comparable to physiological luteal phase values, proving that transdermal cream effectively delivers bioavailable progesterone.

3. Quality of Life & Mood Support

A clinical investigation published in Menopause followed postmenopausal women using transdermal progesterone and reported notable benefits in overall well-being, reduction in nervous tension, and self-reported quality-of-life scores.

Crucial Clinical Notice Regarding Uterine (Endometrial) Protection

According to position statements from The Menopause Society and the American College of Obstetricians and Gynecologists (ACOG), over-the-counter transdermal progesterone creams should not be relied upon alone to protect the uterine lining (endometrium) from hyperplasia if you are taking prescription systemic estrogen therapy. If you have an intact uterus and take prescription estrogen, always work with your physician to ensure adequate prescription-level endometrial protection.

How to Apply: Dosage & Cycling Schedule

Because progesterone naturally rises and falls during normal biological cycles, following a structured application schedule helps mirror your body's natural rhythms.

For Pre-Menopausal & Perimenopausal Women

Goal: Supplement during the luteal phase (the second half of your cycle).

• Massage 1/4 to 1/2 teaspoon twice daily.
• Begin 14 days prior to the first expected day of menstruation (typically Day 12 to 14 of a standard 28-day cycle).
• Discontinue use once your period begins.
• Repeat the same pattern each month.

For Menopausal & Post-Menopausal Women

Goal: Steady support with a monthly rest period to keep hormone receptors sensitive.

• Massage 1/4 to 1/2 teaspoon twice daily.
• Apply consistently for 21 consecutive days.
• Discontinue use for 7 days (one rest week).
• Repeat this 3-weeks-on, 1-week-off routine every month.

Best Application Sites & Rotation Tips

Apply the cream to thin, smooth skin areas with good blood flow. Rotate your application site daily to avoid saturating tissue receptors:

Complete Ingredient Listing & Plain-English Guide

Every ingredient in Source Naturals Eternal Woman Progesterone Cream serves a dedicated purpose—from active hormone delivery to skin conditioning and freshness.

Understanding Safety, Contraindications & California Proposition 65

Why Does This Product Carry a California Proposition 65 Warning?

Under California's Safe Drinking Water and Toxic Enforcement Act (Proposition 65), the state maintains a registry of substances. In 1988, the State of California added progesterone to its Proposition 65 list based on high-dose animal studies and data regarding synthetic progestins used in hormonal therapies.

Unlike synthetic pharmaceutical progestins (such as medroxyprogesterone acetate), Source Naturals Eternal Woman uses bioidentical USP progesterone identical to human physiology. However, because California law requires warnings on any product containing listed ingredients regardless of dosage form or source, this disclosure is displayed for all California consumers.

Precautions & Who Should NOT Use Progesterone Cream:

• Pregnancy and Nursing: If you are pregnant, nursing, or planning to become pregnant, do not use this product without specific guidance from your healthcare professional.
• Hormone-Sensitive Conditions: Women with a medical history of hormone-receptor-positive breast cancer, ovarian cancer, uterine cancer, unexplained abnormal vaginal bleeding, or blood-clotting disorders should consult their physician before using any hormone-containing product.
• External Use Only: Avoid contact with eyes and mucous membranes. Discontinue use immediately if skin redness or irritation develops.
• Keep Out of Reach of Children: Store tightly sealed in a cool, dry place away from heat and direct sunlight.

Frequently Asked Questions (FAQ)

How much progesterone is in each dose of Source Naturals Progesterone Cream?

Each 4 oz jar is guaranteed to contain 500 mg of natural USP progesterone per ounce. A standard serving of 1/4 teaspoon (approx. 1.3 grams of cream) delivers approximately 22 mg of bioidentical progesterone, which closely mirrors the body's natural daily luteal-phase production.

How long does one 4 oz jar of Source Naturals Progesterone Cream last?

A 4 oz jar contains approximately 88 servings of 1/4 teaspoon. When used at 1/4 teaspoon twice daily according to the standard cycling schedules, one jar typically lasts about 1.5 to 2 months.

Where is the best place on my body to apply the cream?

Apply the cream to smooth skin areas where blood capillaries are close to the surface and hair is sparse. The ideal spots include the inner wrists, inner forearms, throat, upper chest, lower abdomen, and inner thighs. Always rotate application sites daily to prevent receptor saturation.

What is the difference between progesterone cream and wild yam cream?

Wild yam root contains diosgenin, a compound that human biology cannot convert into progesterone. Source Naturals Eternal Woman Progesterone Cream contains actual USP bioidentical progesterone that has already been converted to match human progesterone, with wild yam added as a complementary botanical extract.

How soon can I expect to notice results?

Individual responses vary depending on personal hormone balance. Some women report noticeable improvements in nighttime comfort and mood within 2 to 4 weeks, while others achieve the best equilibrium after 2 to 3 consistent monthly application cycles.

Can I use this cream if I am already taking prescription estrogen hormone replacement?

If you are on prescription estrogen and have an intact uterus, medical guidelines specify that over-the-counter progesterone creams should not be substituted for prescription progestogens to protect your uterine lining. Always speak with your prescribing physician before combining over-the-counter hormone creams with prescription therapy.

Scientific References & Clinical Studies

1. Leonetti HB, Longo S, Anasti JN. Transdermal progesterone cream for vasomotor symptoms and postmenopausal bone loss. Obstetrics & Gynecology. 1999 Aug;94(2):225-228. PubMed PMID: 10432133.
2. Hermann AC, Nafziger AN, Victory J, Kulaway R, Rocci ML Jr, Bertino JS Jr. Over-the-counter progesterone cream produces significant drug exposure compared to a Food and Drug Administration-approved oral progesterone. The Journal of Clinical Pharmacology. 2005 Jun;45(6):614-619. PubMed PMID: 15901742.
3. Burry KA, Patton PE, Hermsmeyer K. Percutaneous absorption of progesterone in postmenopausal women treated with transdermal estrogen. American Journal of Obstetrics and Gynecology. 1999 Jun;180(6 Pt 1):1504-1511. PubMed PMID: 10368498.
4. Wren BG, McFarland K, Sanchez L, et al. Transdermal progesterone and its effect on vasomotor symptoms, blood lipid levels, bone metabolic markers, moods, and quality of life for postmenopausal women. Menopause. 2003 Jan-Feb;10(1):13-18. PubMed PMID: 12544672.
5. The 2022 Hormone Therapy Position Statement of The Menopause Society. Menopause. 2022 Jul;29(7):767-794. PubMed PMID: 35797481.