Pen ink is not usually harmful to skin. Pen ink is not usually poisonous in small amounts because it is made from a mixture of dyes, pigments, solvents, and alcohol or water. However, it can be toxic when ingested.
Most modern pen and ink brands are non-toxic, so they do not usually cause significant harm when applied to the skin. However, they can temporarily stain skin. The stain usually goes away after a few days. Some brands of pen and permanent markers contain toxic ingredients like xylene, but these are present in very small amounts and do not usually cause harm when applied to the skin. However, fumes from pens and markers containing xylene can cause eye and nose irritation. Pregnant women should avoid contact with pens containing xylene.
Some kinds of ink can cause poisoning when swallowed. Although a person usually needs to swallow large amounts of ink to get writing ink poisoning, the exact amount can vary depending on age, physical condition and weight, according to the National Institutes of Health. Symptoms of writing ink poisoning include nausea, eye irritation and stained skin. If a child has swallowed lots of pen ink and exhibits symptoms, caretakers should call their local emergency number or the National Poison Control Center.