Pain between the thumb and index finger usually comes from the first dorsal interosseous muscle, a thick wedge of tissue that fills the web space of your hand. This muscle works constantly during gripping, pinching, and typing, making it one of the most overworked muscles in the hand. The good news: most cases respond well to self-massage, stretching, and simple changes to how you use your hands.
What Causes Pain in This Spot
The fleshy area between your thumb and index finger contains two key muscles. The first dorsal interosseous sits on the back of the hand and helps spread your index finger sideways. The adductor pollicis sits deeper, pulling your thumb toward your palm when you pinch or grip. Both muscles can develop painful knots, called trigger points, that produce aching, soreness, and sometimes tingling that radiates into the thumb or along the side of the hand.
The most common culprits are repetitive gripping, prolonged mouse or phone use, and any activity that keeps the thumb and index finger pinched together for long periods. Writing by hand, using scissors, turning keys, and gripping tools all load these muscles heavily. When the muscles stay contracted without enough rest, tension builds and pain follows.
In some cases, the pain points to something beyond muscle tension. Thumb base arthritis affects the joint where the thumb meets the wrist, causing pain during pinching and gripping along with stiffness and swelling. It’s common: about 17% of adults over 50 show signs of it on X-rays, with women affected more often than men (roughly 21% versus 14%). Nerve irritation on the back of the hand can also mimic muscle pain but tends to feel more like burning or shooting rather than a deep ache, and it often comes with tingling or numbness spreading into the thumb and index finger.
Self-Massage for Immediate Relief
The fastest way to ease this pain at home is direct pressure on the sore spot. You only need the fingers of your opposite hand.
- Locate the tender area. Feel the fleshy bulge on the back of your hand between the thumb and index finger. Press around until you find the most sensitive point.
- Apply steady pressure. Squeeze the web space between the thumb and fingers of your other hand. Use the pads of your fingers, not the tips, to press gently but firmly into the sore area.
- Hold for 30 seconds to one minute. You should feel a “good hurt” that gradually fades. If the pain sharpens or feels electric, ease off.
- Release and repeat. Let go, wait a few seconds, then repeat two or three more times.
You can do this several times throughout the day, especially after activities that aggravate the pain. A small massage ball or even a pencil eraser can help you apply more targeted pressure if your fingers get tired.
Stretches That Open the Web Space
After releasing the muscle tension, stretching helps prevent it from tightening right back up. The first dorsal interosseous pulls the thumb and index finger together, so stretching means moving them apart.
Place your forearm and palm flat on a table. Slowly pull your thumb away from your index finger, spreading the web space as wide as comfortable. Hold for 30 seconds, then release. Repeat three to five times on each hand. You should feel a gentle pull through the web space without sharp pain.
Two additional exercises from the Mayo Clinic’s hand therapy recommendations work well here. For the fingertip touch, hold your hand open and slowly bring your thumb to meet each fingertip, forming an “O” shape. Hold each position for five seconds before moving to the next finger. Repeat five times per hand. For the finger walk, place your hand flat on a table, spread your thumb away from your fingers, then slide each finger one at a time toward your thumb. This builds coordination and gently works the small muscles of the hand through their full range.
Reducing Strain From Computers and Phones
If your pain flares during desk work, your setup is likely part of the problem. A standard mouse forces your hand into a palm-down position that keeps the web space muscles constantly engaged. Switching to a vertical mouse or trackball lets you operate the cursor without gripping, which significantly reduces tension in the thumb web space. Place the mouse right next to your keyboard so you’re not reaching sideways for it.
Your keyboard matters too. Keep your elbows at your sides, bent at 90 degrees, with your forearms parallel to the ground. Split keyboards allow each hand to sit at a natural angle instead of twisting inward. Don’t rest your wrists on the desk while typing, as this forces your fingers to reach farther and increases strain throughout the hand. If you spend hours typing, reassigning frequently used keys (like shift, enter, or backspace) to thumb-accessible positions can reduce repetitive finger movements.
For phone use, avoid holding your device in a pinch grip for long periods. Use a pop socket or phone stand, and switch hands regularly.
Splinting and Bracing
If the pain is persistent or related to thumb base arthritis, a splint can take pressure off the area and let it heal. The most commonly recommended type is a short opponens splint, which holds the thumb base in a slightly open position (about 30 degrees of abduction) while keeping the thumb’s middle joint gently bent. This stabilizes the joint without locking up the entire hand, so you can still use your fingers for light tasks.
Prefabricated neoprene thumb splints with a removable metal stay are widely available at pharmacies and online. Wearing one during aggravating activities, or at night if the pain disrupts sleep, often provides noticeable relief within a few weeks.
What About Injections
For thumb base arthritis specifically, cortisone injections are a common recommendation, but the evidence is surprisingly weak. A network meta-analysis comparing cortisone, hyaluronic acid, and platelet-rich plasma (PRP) injections found that none of them outperformed placebo at reducing pain within the first three months. At the six-to-twelve month mark, PRP showed some advantage over cortisone and placebo, but the results came from only two studies and may not be clinically meaningful. In short, injections might help some people, but they’re far from a guaranteed fix.
Signs of Something More Serious
Most web space pain is muscular and resolves with the strategies above. But certain patterns suggest you should get it evaluated. Visible muscle wasting in the web space, where the fleshy bulge shrinks and looks flattened compared to your other hand, can indicate nerve compression. Numbness or tingling that doesn’t go away, especially if it spreads into multiple fingers, points toward a nerve issue rather than simple muscle tension. Weakness that causes you to drop objects or struggle with buttons also warrants attention, as permanent nerve and muscle damage can develop without treatment. Pain that steadily worsens with activity and takes longer and longer to settle with rest could indicate a compartment issue in the muscle itself, particularly if the web space feels tight or swollen during flare-ups.