If something in your apartment has made you sick, you may have a remedy against the landlord if it was caused by a known illness-inducing substance such as lead, asbestos, mold or other known materials that cause illness. While state laws vary, most states require landlords to either disclose certain known materials, like lead, in the home, or to remediate unhealthy conditions before renting to a tenant. Otherwise the landlord may be liable to the tenant. There are some exceptions to this rule, however. If you believe your illness was caused by something harmful in your rental, notify your landlord in writing immediately and ask them to remedy the situation. If your landlord refuses, document the substance with photos and keep records of any visits you make to the hospital. Simply moving out might constitute a breach of your lease agreement. In serious cases, legal counsel may be needed.