Biotin is an essential cofactor for a lot of different reactions that occur in our body. Even if biotin deficiencies are pretty rare, it is possible that those suffering from this disease, exhibit problems with their hairline as well as nail beds so supplementation may be necessary. In our previous investigations, we have found out that biotin for hair growth is a possible solution as long as a patient has an underlying biotin deficiency. It will not be an effective supplement for hair loss treatment if your biotin levels are normal. Even if the universal supplementation of biotin may not work for hair loss, that doesn't mean that is it useless when it comes to brittle nails. Here, we will focus on the question of "can biotin strengthen my brittle nails?"
What Causes My Brittle Nails?
Brittle nails are a common occurrence in the population and are seen in about 20 percent of the global population. It is significantly more common in females than in males and even though there are several claims on the internet stating that biotin will be an efficient way to alleviate your brittle nails, the most likely risk factor that medicine has identified for brittle nails is due to dehydration. 
Onychodystrophy is the more formal name of this disease, and it can be caused by many different conditions, either from infectious or noninfectious diseases. It may also appear as a sign of more serious systematic disorders. Therefore, you need to make sure your doctor checks you thoroughly before you merely settle on biotin to treat your condition.
Another potential cause of your brittle nails stems from medications that you may be ingesting. Known side effects of drugs like anti-malaria medication, remedies for arthritis and anti-HIV medications all have common substances that can cause your nails to become more brittle. The mechanism for why this happens is poorly understood, but it is believed that the medications could cause a combination of inflammation, edema or could even impact nail bed maturation and manifest as nail brittleness. 
This is much more than just a simple problem of breaking a nail every once and a while because studies show that people with fragile nails typically have a dramatically lower quality of lives compared to healthy individuals. Simple activities like fastening buttons, tying shoes and picking up small coins can all be impossible tasks based on nail bed stability. Patients are also predisposed to numerous opportunistic infections if their nails are not strong, so this can manifest as a severe condition. 
Will Biotin Make a Difference?
The main question now is "can biotin strengthen my brittle nails" regardless of the underlying etiology. In one study conducted in Switzerland, this question was put to the test in a population of patients suffering from brittle nails. In the study, there were 44 patients enrolled, and 35 of them were given daily supplementation of biotin for a 6-month period to determine the long-term effect on the thickness of their nails. At the conclusion of the study, 22 of the 35 patients (63 percent) showed clinical improvement while the other 37 percent showed no difference in their symptoms whatsoever. This result suggests that biotin may be useful when dealing with brittle nails, but it is not a resounding success you would hope to see in this type of study. 
In another investigation, researchers determined that biotin could make a difference in some patients in regards to nail thickness, but this largely depended on whether the patients had an underlying biotin deficiency. This result is the same conclusion that we reached when we were investigating the effectiveness of biotin for hair growth. When a more systemic disease is causing the brittle nails or if it is a side effect of medications, the daily supplementation of biotin will not help re-establish firm nails. 
A more promising alternative that has emerged as a treatment option for brittle nails goes by the name of Hydroxypropyl-Chitosan (HPCH). This is a compound that creates a synthetic nail lacquer on the surface of the nails to increase the stability and help the nails regenerate.
Hydroxypropyl-Chitosan (HPCH) essentially creates a medical manicure to put it in more digestible terms. In an investigation to determine the effectiveness of this product, 44 women with brittle nails were tested and researchers concluded that HPCH made a difference in 74 percent of the patients who used the product. Another impressive observation was that the more severe the damage was to the nail bed, the more likely HPCH could provide a therapeutic benefit. 
When trying to find a treatment option for your brittle nails, my suggestion is to try something more definite than biotin for your therapy. Even if it is marketed as a hair loss treatment and as a brittle nail aid, the scientific data does not support these claims definitively unless you have an underlying biotin deficiency.