Patients and friends tell me it’s sometimes difficult to decide exactly what symptoms merit a doctor’s appointment. I find that it helps to think of three basic categories of visits. One category is the all-important annual checkup, which assesses and promotes overall health and can detect signs of early disease. Another category is the follow-up appointment to track chronic conditions or recovery from a major illness.

But the third category — addressing a new symptom of concern — can be a little trickier. Most of us are more emotional than rational when it comes to our health. Our upbringing, our past experiences with illness, our fears and our personality type all color our decision to see a doctor. Ideally, when a new symptom occurs, we calmly tune into it, have the right amount of concern, and get help, if needed, at the right time. A good example is calling 911 for the life-threatening symptoms of a heart attack, which can include sudden chest pressure, shortness of breath, lightheadedness and sweats.

However, emotions and denial can get the best of us. I’ll never forget one gem of a patient, a beloved, newly retired pediatrician, who was finally ready to enjoy free time with his wife. In retrospect, his wife said he minimized the onset of new, but slight, chest discomfort. The discomfort increased on and off for nearly two weeks before he collapsed in their living room from a massive heart attack and could not be revived by the paramedics. Even doctors can go into symptom denial. Sadly, he did not seek the early help that modern cardiology could have provided.

But other symptoms are not so obvious, and it really is difficult to know when to be concerned and how soon to be seen. One tip — if in doubt, call your doctor’s office. Often a nurse or physician’s assistant can talk to you on the phone and help you decide if your symptoms merit a visit. But if the symptom is sudden and seems life-threatening, please call 911.

So how can you know when a new symptom is a sign of a serious disease or just a minor annoyance? Look at it this way: Symptoms are your body’s way of letting you know something is amiss. We each have millions of nerve endings reaching out into every organ, sensing and listening for something that may go wrong inside us. Be aware and try to respond appropriately.

It helps many people to think of three stages of symptom concern:

1. Pre-symptom, no-concern stage — A disease has started brewing inside you, but it is too early for your body to warn you with a symptom. You don’t “feel it,” but that annual check-up may detect it. Examples include a painless breast or testicular lump; elevated blood pressure, cholesterol or blood sugar; or the painless blackish mole of a melanoma. Many diseases can be detected early from the health screening tests your doctor recommends. The good news is, caught early — before you feel any symptoms — many diseases can be cured.

2. Symptom and low-concern stage — You feel a symptom, but have low concern. It could be a common, self-treatable symptom, such as nasal congestion, sore throat or a cough from the common cold. Sometimes the best advice is watch and wait. But more serious symptoms — chest pain, unexplained weight loss, a deep cough and fever — merit more attention, and this is where people vary greatly. Some people pay more attention to their bodies and become concerned sooner. Others tend to ignore their bodies or have a strong psychological denial tendency, telling themselves a story to make the symptom seem less important. These people present to their doctor later, or even take their symptom to the grave.

3. Symptom and high-concern stage — In this stage, most people take appropriate action. They may call a friend or consult Dr. Google first, but will make their way to see their doctor sooner than later. Some people worry excessively; their brain is just wired that way. They may get highly concerned even over the mildest symptoms, thinking worse-case scenarios. This is where a careful history and good doctor-patient rapport can help decipher the serious from the not-so-serious symptoms, detecting an early disease while saving the worrying patient unnecessary distress or excessive intervention.

There are so many reasons to see your doctor that there can be no one recommendation. But see your doctor if you have a new bothersome symptom that comes on suddenly, or a symptom that gets progressively worse, or if you just have a gut sense that something is wrong. Trust your gut — your body is speaking to you.

Rick Donahue is a clinical instructor at Harvard Medical School with 20 years of experience delivering complete primary care. His private practice in Back Bay, MA, Personal Health MD is dedicated to providing comprehensive state of the art primary care.

Submit a guest post and be heard on social media’s leading physician voice.