Because of increasing awareness of the potential dangers of sodium hydroxide found in traditional relaxer formulas, many women have begun abandoning them. "No-lye" relaxers have become increasingly popular. "No-lye" relaxers are of three main types. One type operates on the same general principle as lye relaxers but uses a slightly weaker alkaline agent, such as potassium hydroxide, lithium hydroxide or guanidine hydroxide. The last of these is not pre-formulated, but rather is generated at the time of use by combining a cream containing calcium hydroxide (slaked lime) with an "activating solution" of guanidine carbonate.
Another type of "no-lye" relaxer uses ammonium thioglycolate, which is also known as perm salt for its use in permanent waves. Perm salt is a chemical reducing agent which selectively weakens the hair's cystine bonds instead of disrupting the entire protein, but strips out the natural oils even more thoroughly than the alkali hydroxide products. Afterward, the thioglycolate must be oxidized with a special solution of hydrogen peroxide or sodium bromate.