Pain on the outer side of the foot, also known as lateral foot pain, can start before, during, or after movements or other activities like running or walking. The pain can range from annoying to debilitating. 

When lateral foot pain is severe, burning, or stabbing, it can prevent you from performing activities such as standing, walking, working, or exercising. Luckily this type of pain is not common as other foot pains, like heel or toe pain provoked by plantar fasciitis. 

Pain on the outer side of the foot is characterized by different symptoms including: 

- Swelling

- Difficulty standing on the foot 

- Tenderness

- Difficulty walking 

- Pain on the outer side of the ankle

- Instability of the foot

- Susceptibility to ankle sprains 

Given that lateral foot pain has a number of causes, it can be difficult to correctly identify the source of the pain. If your lateral foot pain doesn’t get better with rest or worsens, you need to seek medical attention. Your healthcare provider will provide you with an accurate diagnosis and recommend the best treatment for you. 

Let’s look at the most common reasons for pain on the outer side of the foot:

1. Stress fractures 

Stress fractures typically result from overuse and often affect teenage athletes and those during their 20’s. They also happen in those who have had a sudden increase in training, wear shoes with improper stability, or lack bone health nutrients such as calcium or vitamin D. 

Since stress fractures tend to progress, they often require surgical intervention to be treated by the time they’re seen in a doctor’s office. 

2. Achilles tendinitis 

The Achilles tendon is the largest and strongest tendon in your body that attaches the calf muscles to the heel bone. Although tendon injuries usually cause pain at the back of the heel, they can contribute to lateral foot pain as well. 

3. Arthritis 

Arthritis leads to inflammation and pain in the joints and is considered a common reason for lateral foot pain. Osteoarthritis, also called wear-and-tear arthritis, causes erosion of the cartilage that reduces friction between bones. This results in stiffness and pain. 

Rheumatoid arthritis is an autoimmune condition, in which the immune system starts to attack the lining that protects the joints (called synovium) leading to swelling and damage to the bones, cartilage, and other supporting structures of the joint. 

Arthritis-induced lateral foot pain is characterized by redness and warmth at the joint. The pain may get worse with activity. 

4. Peroneal tendonitis 

Injuries to the peroneal tendons are a common thing. Peroneal tendinitis is actually the second most common reason for lateral foot pain. The hallmark of this issue is pain that comes on gradually. 

Athletes, especially long-distance runners are more likely to develop peroneal tendonitis, but the condition can also occur in people with muscular imbalance, high arches, or a previous ankle injury. 

5. Ankle sprains 

Ankle sprains are the most common culprits of pain on the outer side of the foot and are more common in people who have high arches. They typically happen during activities that make the foot roll, twist, or suddenly change directions, such as volleyball, basketball, and trail running, or hiking on uneven surfaces. 

When the foot twists, it can lead to a tear in a ligament that supports the ankle bones. In addition to pain, ankle sprains are usually accompanied by bruising or swelling and tenderness. If the sprain is severe, you might hear a popping sound. 

It’s essential to treat an ankle sprain promptly, otherwise, it may contribute to chronic disability. It’s also important to note that a previous ankle sprain is a risk factor for more ankle sprains.