Hegu (Large Intestine 4) is an acupoint in the webbing between the thumb and index fingers. It is considered one of the most commonly used acupoints and with good reason. LI-4 has a wide range of uses, particularly pain relief all over the body. Here are some conditions this acupoint is known to treat: abdominal pain, headaches, hay fever, allergies, itchy eyes, constipation, stiffness of the arm and shoulder, addictions, and panic attacks.
It is also a point used for gynecological conditions such as PMS, delayed or irregular periods or no periods. This point is a FORBIDDEN point, meaning it should NOT be used during pregnancy. It is known to trigger uterine contractions. If you are trying to get pregnant, do not use this point after ovulation. However, before ovulation it calms the uterus, moving stuck energy and calming the mind which is helpful in balancing the reproductive system in cases of infertility. I don't personally recommend using this point for the pain of dysmenorrhea (pain during period) — it can trigger uterine contractions that may worsen the pain.
To use this point, simply massage between the webbing for a minute, gently pulling your thumb from the webbing to the end of the crease (see photo). You may find this point is a little tender. Remember, since acupressure is an energy system, you don't need to use much pressure to access these points.