Several types of medications can cause brittle, splitting, or thinning nails. Chemotherapy drugs and oral retinoids are the most consistent culprits, but targeted cancer therapies, blood pressure medications, and a handful of other drug classes can also damage nail structure. The changes typically appear within weeks of starting treatment, since nails grow slowly and damage to the nail’s growth center takes time to become visible at the surface.
Nails are produced by a cluster of cells called the nail matrix, tucked under the skin at the base of each nail. Medications that reach this area through your bloodstream can disrupt how new nail cells form, leading to thinner, more fragile plates. Some drugs also affect the nail bed underneath or reduce blood flow to the fingertips, both of which weaken nails over time.
Chemotherapy Drugs
Cancer chemotherapy agents are among the most common medication causes of nail problems. These drugs target rapidly dividing cells, and because nail matrix cells divide quickly, they’re caught in the crossfire. The result can range from mild ridging and discoloration to painful nail lifting and bleeding underneath the nail plate.
Taxane-based chemotherapy drugs are particularly well documented. In a study of 79 patients experiencing nail side effects from taxanes, paclitaxel accounted for nearly 89% of cases. About a third of patients had mild changes like horizontal grooves (called Beau’s lines), small hemorrhages, or painless nail lifting. But 63% developed more serious problems, including painful bleeding under the nail and significant inflammation around the nail folds. A small percentage progressed to infections and overgrowth of raw tissue around the nail.
Other chemotherapy classes can cause similar damage. The general pattern is the same: the drug disrupts normal nail production, and within a few weeks you may notice grooves, discoloration, or increased fragility across multiple nails, sometimes all 20.
Oral Retinoids
Oral retinoids, prescribed for severe acne and certain skin conditions, are the other drug class most reliably linked to nail thinning and brittleness. These medications cause diffuse damage to the nail matrix, resulting in thinner nail plates that split and peel more easily. The effect tends to build with long-term use rather than appearing suddenly.
Unlike chemotherapy, where nail damage is an accepted trade-off for treating cancer, retinoid-related nail fragility sometimes prompts a conversation about dose adjustment. The nails gradually recover once the medication is stopped or reduced, though this takes months because you have to wait for an entirely new nail to grow out from the base.
Targeted Cancer Therapies
A newer generation of cancer drugs that block a protein involved in cell growth (EGFR inhibitors) causes a distinctive pattern of nail and skin problems. Medications in this group, including gefitinib, erlotinib, and cetuximab, frequently trigger painful inflammation around the nail folds that can progress to overgrowth of raw, fragile tissue resembling ingrown nails. Discoloration, white streaks, and dark streaks on the nails are also common.
These nail changes are part of a broader set of skin side effects that occur regularly with these drugs, including acne-like rashes, dry skin, and itching. The nail problems tend to start with redness and swelling around the nail edges before affecting the nail plate itself.
Blood Pressure and Heart Medications
Beta-blockers, commonly prescribed for high blood pressure, heart rhythm problems, and anxiety, can impair blood flow to the fingertips. Reduced circulation to the digits means the nail matrix receives less oxygen and fewer nutrients, which can gradually weaken nail structure. In more pronounced cases, this restricted blood flow leads to noticeable nail changes alongside cold or discolored fingertips.
This mechanism is different from direct toxicity to the nail matrix. Rather than poisoning the cells that produce your nail, beta-blockers starve them by narrowing the small blood vessels that feed your fingers. The effect is generally milder than what chemotherapy causes, but over months of use it can contribute to nails that crack, split, or break more easily than they used to.
How Quickly Nail Changes Appear
Fingernails grow roughly 3 to 4 millimeters per month, and toenails even slower. When a medication damages the nail matrix, the affected portion of nail won’t reach the visible part of your finger for several weeks. Horizontal grooves and ridges typically show up across all nails within weeks of starting treatment. Other changes like lifting, splitting, or overall thinning may take longer to become obvious.
This delay also works in reverse. Once you stop the medication responsible, your nails won’t immediately improve. You’re waiting for the damaged nail to grow out completely and be replaced by healthy nail produced after the drug cleared your system. For fingernails, that process takes roughly four to six months. Toenails can take a year or longer.
Managing Brittle Nails During Treatment
Stopping the medication isn’t always an option, especially when the drug is treating cancer or another serious condition. In most cases, doctors recommend continuing the medication and managing nail symptoms with supportive care. Dose reduction or stopping the drug is reserved for severe nail toxicity that significantly affects daily function or leads to infection.
Practical steps that help protect fragile nails include keeping them trimmed short to reduce leverage that causes cracking, wearing gloves during housework or any task involving water and chemicals, and avoiding nail polish removers with acetone. Moisturizing the nails and cuticles regularly with thick emollients helps maintain flexibility in the nail plate and reduces splitting.
Specialty nail lacquers containing hydroxypropyl chitosan have shown promise in improving nail growth rate and keratin quality during chemotherapy. These are applied like clear nail polish and work by reinforcing the surface of the damaged nail plate.
Biotin Supplementation
Biotin (vitamin B7) is the most studied supplement for brittle nails. Research has demonstrated a 25% increase in nail plate thickness in people with brittle nails who took daily biotin supplements. The improvement takes time, typically three to six months of consistent use, because you need to wait for new, thicker nail to grow in. Biotin appears to work by supporting the production of keratin, the protein that makes up the nail plate. It’s worth noting that biotin can interfere with certain lab tests, so let your doctor know if you’re taking it before any bloodwork.
Recognizing Drug-Related Nail Damage
A few patterns suggest your nail changes are medication-related rather than caused by a nutritional deficiency, fungal infection, or normal aging. Drug-induced nail problems tend to affect multiple nails at the same time, often appearing on all fingers rather than just one or two. They also correlate with the timing of a new medication, showing up weeks to a couple of months after you start treatment. Horizontal grooves that run across the nail at the same level on several fingers are a classic sign of a systemic disruption, essentially a timestamp marking when the drug first affected nail production.
If only one or two nails are affected, or if the changes developed gradually without any medication changes, other causes like repetitive trauma, fungal infections, or thyroid problems are more likely explanations.