Hormone types

One of the first choices you may need to make is an almost philosophical one: you need to decide the broad type and source of the hormone(s) you will take. HRTs fall into three general categories, and we'll look at them one at a time.

Human identical

Human identical hormones are those whose chemical structure is identical to the hormones your own ovaries made. As such, they can be expected to act in your body just as your own endogenous hormones did. Not only are they used in the same way, but they are broken down and eliminated from the system in the same way.

This confers the benefit of generally causing fewer undesirable effects than synthetic hormones, since all of the breakdown products are metabolized into weaker and weaker forms until they are eliminated naturally.

The body can, however, also take these human identical hormones and convert them, just as it did with endogenous hormones, to other hormones and chemicals within the body when it needs those more. Whether or not that is an asset or liability depends on what that ends up doing to your overall hormone status, something we'll look at more in the section on balancing doses.

Many women find the idea that these hormones do no more and no less than their own a compelling attraction. All of the currently-available human identical hormone preparations are derived from plant sources and are refined in the lab to reach the correct molecular configuration.

Another term that is often used for this type of hrt is "bioidentical." We don't use that term on this site because it's also used by compounding pharmacists and some physicians to describe their practice of testing and prescribing multiple hormones. Rather than keep specifying which one we're talking about, we just prefer the "human identical" phraseology.

When looking at HRTs, you may sometimes notice that the active ingredient name in the drug pamphlet is not just the hormone name, such as "estradiol," but rather something like "estradiol sulfate" or some other compound. These are simply stabilizing forms that the hormones are made up in so that they can be conveyed into the body and processed into active bioidentical hormones. In other words, these are part of the delivery system, not how the hormones function once in our bodies. On our specific HRTs pages, we'll identify which are which.


Synthetic hormones are those that are similar to but not identical to our endogenous hormones in molecular structure. They have been demonstrated by the manufacturers to produce at least some of the same general actions as our own hormones in the body, but they may not perform all of the functions of our own hormones.

In addition, because they have extra molecular bits of structure that our bodies are not equipped to process, these bits of unusable structure can float around our system causing side effects of various kinds. Some of these side effects can be miserably uncomfortable for some women, such as migraines, or acutely dangerous, such as hypertension.

Some synthetics, unlike bioidenticals that get weaker at each breakdown stage, actually produce stronger compounds as the body metabolizes them. Those compounds may persist in the body for some time, building up or even persisting long after the hormone has been discontinued, an important factor to keep in mind when beginning or ending taking these HRTs.

On the other hand, in some cases this inability of the body to process these compounds normally may be beneficial, as in a woman whose body uses so much of the hormone to create other compounds that she is unable to keep enough for the primary hormonal use. In other cases, the fact that the hormonal effects of a synthetic may be more limited can confer a therapeutic benefit where the synthetic avoids producing an effect that would otherwise be damaging—such as stimulating some forms of cancer.
Because some synthetics are obtained from animal sources, there are also women who have ethical objections to their use. Most synthetics, however, are now derived from plant sources (and we'll tell you which ones are which in our specific HRT pages).


Alternative hormones are those that are least like our own hormones but still exert a limited hormonal effect. In this category are herbal preparations and foods, which contain phytoestrogens and other active compounds.

While many women find it more "natural" to obtain hormones, as they do nutrients, from unprocessed plant sources, we'll admit right up front that we have some significant problems with this concept.
To begin with, the actual hormonally-effective ingredient in many preparations sold as hormonal agents has not been identified, tested, or even quantified. While that might not be too much of a problem for a woman in natural menopause, for a woman dependent upon a steady supply of exogenous hormones, unregulated and unreliable supplies of supplements may not provide the dependable source she needs.

In other cases, testing has failed to identify any hormonally-active ingredient in popular herbal remedies. Some, such as soy, interfere with the function of other hormones—in this case, the thyroid. Some, when taken steadily and over a long period of time, may cause liver and other physical damages. For some hormonal actions, there are no herbal alternatives that are effective. And for all alternative hormones, just as with all prescription HRTs, if it is capable of acting in the body to fulfill hormonal functions, it is also causing hormonal risks: these no more qualify as a free lunch than any other aspect of HRTs. A woman who cannot take prescription HRTs is placed in just as much risk by taking alternative ones.

Frankly, we don't see why taking hormones natural to a plant (that are developed as hormone-disrupting defenses for the plant against animals) is preferable to taking the exact hormones that are native to our bodies. Now, before you click away in a huff, rest assured: while we don't think that alternative hormones are the most effective of all choices, we will hotly defend each woman's right to make up her own mind as to what is right for her.

If this is what you want and you are happy and healthy with your choice, we salute you. All we ask is that you study what you are taking, understand its risks and limitations, and make your choices deliberate ones. TANSTAAFL.

Why we don't use the term "natural" here

It's overused in advertising and there is no consistency in how it's defined. Some women, pharmacists, doctors, other practitioners, and popular authors and entertainers use it to signify human identical; others use it to mean unrefined plant products that are sold without prescription and may contain some hormonally-active compounds.

Because we don't assume that everything found in its natural state is "safe," we find that particular implication in alternative HRT advertising deceptive: if you think that everything that grows is safe, we'd like to introduce you to our friends water hemlock and amanita mushrooms, who will not be joining us for lunch.

For clarity, then, we avoid the term and all of its varied implications. We'd rather talk about what's really important to hormone function: how the actual molecules compare with the ones our ovaries made and how that affects how they perform in our bodies.