Oxymetholone is a potent oral anabolic steroid derived from dihydrotestosterone. More specifically, it is a close cousin of methyldihydrotestosterone (mestanolone), differing only by the addition of a 2-hydroxymethylene group. This creates a steroid with considerably different activity than mestanolone, however, such that it is very difficult to draw comparisons between the two. For starters, oxymetholone is a very potent anabolic hormone. Dihydrotestosterone and mestanolone are both very weak in this regard, owing to the fact that these molecules are not very stable in the high enzyme (3-alpha hydroxysteroid dehydrogenase) environment of muscle tissue. Oxymetholone remains highly active here instead, as is reported in standard animal assay tests demonstrating a significantly higher anabolic activity than testosterone or methyltestosterone. Such assays suggest the androgenicity of oxymetholone is also very low (1/4th to 1/7th its anabolic activity), although real world results in humans suggest it is decidedly higher than that.
Oxymetholone is considered by many to be the most powerful steroid commercially available. A steroid novice experimenting with this agent is likely to gain 20 to 30 pounds of massive bulk, and it can often be accomplished within 6 weeks of use. This steroid produces a lot of water retention, so a good portion of this gain is going to be water weight. This is often of little consequence to the user, who may be feeling very big and strong while taking oxymetholone. Although the smooth look that results from water retention is often not attractive, it can aid quite a bit to the level of size and strength gained. The muscle is fuller, will contract better, and is provided a level of protection in the form of extra water held into and around connective tissues. This will allow for more elasticity, and will hopefully decrease the chance for injury when lifting heavy. It should be noted, however, that a very rapid gain in mass might also place too much stress on your connective tissues. The tearing of pectoral and biceps tissue is commonly associated with heavy lifting while massing up on steroids, and oxymetholone is a common offender. There can be such a thing as gaining too fast.