Study register / Autonomic / Other / Long COVID

Long COVID

2 curated studies · 2 key studies · mechoulam.de

For long COVID, only two small controlled trials exist so far, and they showed no clear benefit. Research in this area is still at a very early stage.

Rating scheme

The letter rates the quality of a study, independently of its type. Every study type can receive any grade: a review can be B or C when it is small or weak, and an RCT can be S. The grade is a synthesis of study design, journal authority and clinical bindingness:

S
Highest evidence, large, methodologically first-rate studies or S3 guidelines
A
Strong evidence, solid, meaningful studies with a clear result
B
Moderate evidence, smaller or methodologically limited studies
C
Weak evidence, preliminary, indirect or contradictory findings
D
Lowest evidence, exploratory hints, single cases or expert opinion

Quality profile per study

To the left of each study there is a profile of four features, it shows the differences within a letter class.

Sample size ★
Number of participants (RCT) or included studies (review).
Blinding
Double-blind, single-blind or open-label.
Effect size
Clear benefit, mixed, no benefit or harm.
Citations / year ★
Age-adjusted citation frequency.

Key studies

2
  1. 01
    B
    Impact of combined plant extracts on long COVID: An exploratory randomized controlled trial.
    Lukkunaprasit et al. ·2024 ·Complementary therapies in medicine
    Read
  2. 02
    C
    A Single-Blind, Randomized, Placebo Controlled Study to Evaluate the Benefits and Safety of Endourage Targeted Wellness Formula C Sublingual +Drops in People with Post-Acute Coronavirus Disease 2019 Syndrome.
    Young et al. ·2024 ·Cannabis and cannabinoid research
    Read

Randomised Controlled Trials

Efficacy and safety evidence from controlled interventional trials.

2
B
Sample size ★★★★★
Blinding Double-blind
Effect size Mixed
Citations / year ★★★★★
● Key study
Lukkunaprasit et al. ·2024 ·Complementary therapies in medicine
2 citations

Impact of combined plant extracts on long COVID: An exploratory randomized controlled trial.

Design
RCT
Sample
n = 66 Pat.
Key finding

The intervention reduced the total symptom score and moderate to severe symptoms (particularly fatigue and post-exertional malaise), but not CRP levels or quality of life.

Summary

n=66 Long COVID patients, combined plant extract (including Cannabis sativa) 4500 mg/day vs. placebo over 7 days. No significant CRP effect [MD=-0.05 mg/L, 95% CI (-0.49, 0.39)], but reduction in total symptom score [MD=-4.00, 95% CI (-7.58, -0.42)], moderate-severe fatigue [RR=0.25, 95% CI (0.08, 0.81)] and post-exertional malaise [RR=0.35, 95% CI (0.16, 0.78)]. Mild-moderate side effects.

DOI 10.1016/j.ctim.2024.103107 ↗
C
Sample size ★★★★★
Blinding Single-blind
Effect size Mixed
Citations / year ★★★★★
● Key study
Young et al. ·2024 ·Cannabis and cannabinoid research
7 citations

A Single-Blind, Randomized, Placebo Controlled Study to Evaluate the Benefits and Safety of Endourage Targeted Wellness Formula C Sublingual +Drops in People with Post-Acute Coronavirus Disease 2019 Syndrome.

Design
RCT
Sample
n = 31 Pat.
Key finding

Both groups showed improvements in PGIC and PROMIS scores at day 28, but the placebo control was compromised, as the placebo formulation unexpectedly contained high terpene concentrations and was not a true placebo.

Summary

n=31 Post-Acute COVID-19 Syndrome (PACS), CBD-rich full-spectrum preparation (Formula C) vs. placebo over 28 days, then crossover to open-label active treatment (further 28 days). n=24 completers, 8 discontinuations (not product-related). PROMIS and PGIC scores improved in both groups from day 28; post-hoc placebo analysis unexpectedly showed medicinal terpene concentrations (not a true placebo). Improvement persisted in the open-label phase. No safety events.

DOI 10.1089/can.2022.0135 ↗