SIDE EFFECTS & RISKS
A. Irritant-contact Dermatitis
You may experience mild burning or stinging sensation, itching, minor redness, or irritation of skin at the application site. If HQ has been applied around eyes or nose, you may also experience dryness or cracking of the skin. In a study, cosmetic formulation containing 2% HQ has known to produce mild irritation reactions positivesensitization reactions.
But more severe reactions can also occur. These include the feeling of more extreme burning, itching, crusting, or swelling of treated areas. You may even notice unusual skin discolouration. And although rare, a blue-black darkening of the skin may occur.
B. Allergic-contact Dermatitis
Many HQ products contain sodium metabisulphite that may cause serious allergic reactions. These include minor hives, itching,
wheezing, severe asthma attack and even anaphylaxis in certain susceptible people. So if you have sulfite allergy, pay careful
attention to the labels. Product such as Esoterica contain sodium bisulfite or sodium metabisulfite.
In severe allergic reactions, you may experience excessive dryness and cracking, redness, stinging or blue-black darkening of the skin. Others severe reactions include rash, hives, blistering, difficulty breathing, tightness in the chest or swelling of the mouth, face, lips, and tongue.
In cases of dermatitis due to HQ, removal from exposure will quickly clear up the symptoms.
Sometimes, instead of lightening the skin, HQ have been linked to ochronosis—a progressive sooty darkening and thickening of the skin that has been exposed to HQ. Most reports have been particularly in people of color, and after prolonged period of daily use—sometimes 10 to 40 years—of high concentrations HQ. Nevertheless, even short-term use of HQ-containing cosmetics in black people of South Africa, Britain, and the U.S. have observed dome-shaped yellowish spots and grayish-brown spots.
Histologically, degeneration of collagen and elastic fibers occurs, and is followed by the appearance of characteristic ochronotic deposits consisting of crescent-shaped, ochre-colored fibers in the dermis.
D. Cancer & Leukemia
Although its cancer-causing properties have yet to be proved in humans and, HQ has been known to cause mutations in research lab—liver cancer and leukemia in rats. Also, its strong implication to produce leukemia is associated with benzene exposure—in leukemia the hematotoxicity of benzene causes DNA and chromosomal damage. Hence in 2006, the FDA proposed a ban on over-the-counter sales of HQ-products due to these studies that indicated HQ acting as a carcinogen.