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How can I tell the difference between allergies and COVID symptoms?

Question: I have a persistent itchy throat. I spend a lot of time outdoors and think my issue is allergies, but how can I tell the difference between allergies and COVID symptoms? What are common COVID symptoms?

Answer: We talked about this allergy/COVID symptom differentiation issue a long time ago — back in our Q&A of 3/14(!) — but we know a lot more now, and some of what I wrote back then is no longer correct, so let’s revisit. First, I’m not a doctor and if you have any health concerns, please talk with your doctor. Second, CDC recently updated its list of COVID symptoms based on new evidence (Table 1). As you’ll see on this list, there are some overlaps with symptoms of common allergies, but some differentiation. For example, if your throat is scratchy (rather than sore), that’s not a sign of COVID. In early May, the World Allergy Organization Journal published this statement paper from the European Forum for Research and Education in Allergy and Airway Diseases, which describes commonalities and major differences between COVID and allergy symptoms (Figure 1). Upshot is, itchy throat==allergies.

When you look at the list of COVID symptoms (Table 1), it may also be helpful to understand how common each of the listed symptoms is. Unfortunately, CDC does not provide such information, which could be because it’s still too early in our understanding to give these types of estimates. Nonetheless, because I’m interested, I pulled a few pieces of data from recent research. Table 2 shows frequency of symptoms among children and adolescents who participated in a European cohort study. Among children and adolescents, the most common symptoms were fever (65%) and upper respiratory tract infection (54%) (diagnosed based on congestion/runny nose, sore throat, ear ache. cough, sinusitis). CDC shares more information on pediatric clinical presentation here. For adults, the European CDC offers a nice synthesis of recent evidence, which I’ve copied here for ease of reference:

  • An Observational study of 1,420 patients with mild or moderate disease indicated that the most common symptoms were headache (70%), loss of smell (70%), nasal obstruction (68%), cough (63%), fatigue (63%), muscle pain (63%), runny nose (60%), gustatory dysfunction (54%) and sore throat (53%), and fever (45%).
  • The International Severe Acute Respiratory and Emerging Infections Consortium reported on 25,849 hospitalized cases of COVID-19 across a broad clinical spectrum. The five most common symptoms at admission were history of fever, shortness of breath, cough, fatigue/malaise, and confusion.
  • An analysis of data from 4,203 patients mostly from China identified fever (81%), cough (58%), and difficulty breathing (24%) as the most common clinical symptoms.
  • A study among 20,133 hospitalized patients from acute care hospitals in England, Wales and Scotland identified clustering of symptoms with three common clusters: one respiratory symptom cluster with cough, sputum, shortness of breath, and fever; a musculoskeletal symptom cluster with myalgia, joint pain, headache, and fatigue; a cluster of enteric symptoms with abdominal pain, vomiting, and diarrhea. 29% of patients presented with gastrointestinal symptoms on admission, mostly in association with respiratory symptoms, while 4% of patients presented with only gastrointestinal symptoms.
  • A systematic review identified olfactory and gustatory dysfunction as common symptoms with a 53% pooled prevalence across 10 studies with a total sample size of 1,627 patients from North America, Europe and Asia.
  • A pooled analysis of five studies with 817 patients found altered taste sensation was common 50% of COVID-19 patients.
  • Analysis of self-reported symptoms from 7,104 individuals who tested positive and used the COVID Symptoms Study app found, “Loss of smell and taste, together with fever or cough, should now enable us to identify 87.5% of symptomatic COVID-19 cases, although this is likely to be less in the early phases of the infection.”

Table 1. COVID Symptoms (CDC)

  • Fever or chills
  • Cough
  • Shortness of breath or difficulty breathing
  • Fatigue
  • Muscle or body aches
  • Headache
  • New loss of taste or smell
  • Sore throat
  • Congestion or runny nose
  • Nausea or vomiting
  • Diarrhea

Figure 1. Similarities and Differences between COVID and Allergy Symptoms (from EUFOREA Statement)

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Table 2. Frequency of Symptoms in Children and Adolescents (Lancet)

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