Dakin solution, also called Dakin fluid or Carrel-Dakin fluid, is a dilute sodium hypochlorite (NaClO) solution that is commonly known as bleach. The mixture of sodium peroxide (NaO) and hydrochloric acid (HCl) produces sodium hypochlorite. The main active agent in the Dakin solution is created when the chlorine in the solution reacts with water in the environment to form hypochlorous acid (HClO). This hypochlorous acid produces the potent antibacterial effect in tissues. In fact, neutrophils of the human immune system produce small amounts of hypochlorous acid inside phagosomes, which are used to digest bacteria and viruses. Unlike stronger germicidal solutions that contain carbolic acid or iodine, Dakin does not damage living cells or lose potency in the presence of blood serum. It has a solvent action on dead cells that hastens the separation of dead tissue from living tissue.
English chemist Henry Dakin and French surgeon Alexis Carrel developed a Dakin solution to clean and irrigate wounds. It was originally formulated as a battlefield wound antiseptic during World War I. They devised the Carrel-Dakin treatment to irrigate wounds after surgical debridements were performed to preserve and save limbs. As a result of their work, the Dakin solution has saved many lives (and limbs) since its creation. 
The low cost and effectiveness of the Dakin solution make this bactericidal antiseptic very popular in the healthcare field. It is used to treat or prevent infections from cuts, abrasions, laceration, skin ulcers, stage I to IV pressure ulcers, first- and second-degree burns, and even during surgery. Its efficacy has been compared to negative pressure wound therapy for the treatment of diabetic foot ulcer infections. This is why the Dakin solution (usually in a diluted form) continues to be used in practice today. 
Mechanism of Action
Dakin solution is a strong topical antiseptic widely used to clean infected wounds, ulcers, and burns. Full strength Dakin solution is usually diluted in water, depending on its intended use. A 0.5% solution of hypochlorite (containing approximately 5000 ppm free chlorine) is used for disinfecting areas contaminated with bodily fluids, including large blood spills (after the area has been cleaned with a detergent).
Dilute Dakin solution (0.05% to 0.025%) can be used to irrigate, cleanse, or as a component in wet-to-dry dressings to treat or prevent skin and soft tissue infections. 
The mechanism of action of the Dakin solution is mostly unknown, but it acts as a germicidal, bacteriostatic topical agent that can dissolve necrotic tissue debris. Dakin solution is an effective agent against a broad spectrum of aerobic and anaerobic bacteria as well as viruses, fungi, and spores. It has bactericidal activity against a variety of organisms including Enterococcus, Streptococcus mitis, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumonia, Enterobacter cloacae, Serratia marcescens, Proteus mirabilis, and Pseudomonas aeruginosa. It even has been effective against organisms highly resistant to antibiotics such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). 
Due to its properties as an acid-based compound, the Dakin solution can be corrosive to healthy tissue, especially at higher concentrations. An oil-based ointment such as petroleum jelly can be applied to surrounding healthy tissue to reduce skin irritation and prevent debridement of viable tissue. Dakin solution also loses its antiseptic properties rapidly after application due to the instability of the compound. Therefore, gauze sponges soaked with Dakin that are used to pack necrotic wounds need to be frequently changed. It is usually applied once a day on lightly to moderately exudative wounds and twice a day for highly exudative or contaminated wounds. 
The most common side effects of Dakin's solution include redness, swelling, and skin irritation. The main concerns for using Dakin fluid are allergic reactions, skin hypersensitivity, and impaired wound healing, which can occur when using high concentrations of Dakin due to fibroblast toxicity.
Dakin solution often is used in pregnancy and during lactation as there is limited systemic absorption. However, it is classified as a category C agent by the FDA. Dakin has shown adverse fetal effects in animal reproduction studies, but there have been no adequate, well-controlled human studies. For this reason, the potential benefits of the solution in pregnant women warrant its use notwithstanding the possible risk to the fetus.
The labeling on the Dakin solution may cause some confusion for healthcare providers regarding its strength. The labels list strengths as full strength at 0.5%, half strength at 0.25%, and quarter strength at 0.125%. This terminology can cause confusion for healthcare providers who consider the half strength and quarter strength to correspond to 0.5% and 0.25%, respectively. Of note, most hospitals use a modified Dakin solution of 0.025% for wound care, and studies have suggested that concentrations of Dakin solution greater than 0.025% may potentially be harmful to wound healing. 
Contraindications to using Dakin solution include hypersensitivity to sodium hypochlorite, chlorine compounds, or any component of the formulation. Concomitant use of taurolidine (an antimicrobial that is used to try to prevent infections in catheters) may enhance the adverse/toxic effect of sodium hypochlorite. Specifically, concomitant use of taurolidine and sodium hypochlorite may increase the risk of metabolic acidosis. 
Wounds only need to be monitored to assure proper healing. If there appears to be an adverse reaction when applying the Dakin solution, it should be discontinued immediately.
Ingesting diluted sodium hypochlorite generally causes only mild stomach irritation; however, swallowing larger amounts can cause more serious symptoms, including chest pain, delirium, hypotension, burns to the gastrointestinal tract, shock, bradycardia, nausea, and vomiting. The concentration of sodium hypochlorite in industrial-strength bleach is much and may cause severe injury.
It is important never to mix ammonia with sodium hypochlorite (bleach or bleach-containing products). This mixture can produce toxic chlorine gas that can cause choking and serious breathing problems. HCl is formed when chlorine gas contacts moist tissues like the eyes or lungs. HCl is a digestive juice that damages tissue; it can damage the airways, cause asphyxiation, and result in death.
It is important to note that activated charcoal does not effectively treat (adsorb) sodium hypochlorite. Treatment will depend on the severity of the toxicity with medical management for mild-moderate cases of toxicity, to surgery if there are perforations noted along the gastrointestinal tract.
Enhancing Healthcare Team Outcomes
The Dakin solution bactericidal antiseptic is very popular and clinicians, nurses, and pharmacists should be familiar with its use. It is used to treat or prevent infections from cuts, abrasions, laceration, skin ulcers, stage I to IV pressure ulcers, first- and second-degree burns, and even during surgery. an interprofessional team approach to its use will provide the best patient outcomes. [Level V]