Nizoral shampoo contains the synthetic anti-fungal medication ketoconazole in a concentration of 2 percent. People use this shampoo to treat fungal and yeast skin infections such as pityriasis versicolor, seborrhoeic dermatitis and seborrhoeic dandruff, as explained by Net Doctor. Ketoconazole eliminates fungi and yeasts by interfering with their cell membranes. All side effects associated with Nizoral shampoo prove rare.
A small percentage of people experience changes to their hair when using Nizoral shampoo, according to Drugs.com. Abnormal hair texture can develop, along with either oiliness or dryness. Hair with a permanent wave may lose the wave, and hair discoloration may occur, mainly in gray hair or chemically-damaged hair. Some Nizoral shampoo users have experienced an increase in normal hair loss or patchy hair loss (alopecia).
Skin Side Effects
Skin side effects also are possible, although unlikely. Itching, stinging, burning sensations, dryness, pimples and eczema can develop. If you use Nizoral shampoo, keep it away from your eyes because the product is irritating to mucous membranes. If you get any in your eyes, rinse them with plenty of water. Research shows that irritation with ketoconazole 2 percent-strength shampoo is significantly less than that of selenium sulfide shampoo in concentrations of 2.5 percent, such as Selsun Blue, according to Drugs.com.
Severe hypersensitivity or allergic reactions to Nizoral shampoo have been reported, according to Drugs.com. Signs include a rash, severe swelling or shortness of breath. Anyone experiencing these side effects should seek immediate medical attention, because anaphylaxis, a shock reaction which may be life-threatening, can develop. Some people also have experienced allergic skin inflammation (contact dermatitis).
Nizoral shampoo is classified as Pregnancy Category C by the U.S. Food and Drug Administration (FDA), indicating that animal studies show possible harm to the fetus, but research with humans is lacking. With pregnant rats, large amounts of ketoconazole consumed orally caused birth defects. Pregnant women should only use Nizoral shampoo if the potential benefits outweigh the possible risks.