Clinical Trials (in all of the different stages) require a lot of data to display two aspects of the drug: safety and efficacy. If the "drug" has no adverse effects and the data displays positive symptom relief, then it would be acceptable to put it out on the market EVEN if this drug is a placebo. Based on the prompt above, to put the drug out into the market the drug would have to gain approval from the FDA. If the drug DOES gain approval, then the clinical trials must have adequately shown the safety and efficacy of the drug through pharmacokinetics and pharmacodynamics. To simplify my statement, any drug that the FDA approves is allowed to be put into the market. However, it is much much harder to gain approval than the prompt makes it seem, especially when dealing with a placebo product.

The scenario you describe raises several important ethical and regulatory considerations.

1. Efficacy: If a drug is found to cure the common cold only 50% of the time but performs better than a placebo in clinical trials, it may still be considered effective to some extent. However, the level of efficacy and the clinical significance of this improvement are critical factors to consider.

2. Placebo: If the "drug" is essentially a placebo with no active ingredients and yet shows improved recovery times compared to a control group, this could be due to a placebo effect, where patients experience improvements because they believe they are receiving treatment.

3. Ethical Considerations: The use of placebos in clinical trials is subject to strict ethical standards, and their use is generally limited when effective treatments exist. If there are known treatments for the common cold that are more effective, it might not be ethical to introduce a placebo drug to the market, as patients may be better served by existing treatments.

4. Regulatory Approval: Regulatory agencies like the FDA (in the United States) typically require drugs to demonstrate safety and efficacy before they can be approved for the market. The fact that the "drug" is a placebo may raise regulatory concerns, as it does not have an active ingredient to provide the intended therapeutic effect.

5. Informed Consent: Patients have a right to know what they are receiving in a clinical trial. If they are being given a placebo, this should be clearly communicated, and informed consent is necessary.

In summary, whether it would be acceptable to put such a placebo on the market would depend on various factors, including the level of efficacy, ethical considerations, regulatory requirements, and the presence of other effective treatments for the common cold. Introducing a placebo as a treatment in cases where more effective treatments are available could be ethically problematic and may not meet regulatory standards.

Placebo pills work because the person taking its expects that pill to work and it works(sometimes) because of the power of the mind. For instance, stress has been shown to increase blood pressure which can lead to a risk factor such as heart disease so the state of the mind can be controlled so that the patient feels more calm which in turn contributes to the cure effects it has. If a company were to ever advertise and sell this product, it will definitly receive a lot backlash from the market. People would agree its just another scheme from the medical industry that is made to deceive people even though it may help with someone's symptoms. Or it may have some unwanted side effects known as the nocebo effect where negative effects can be triggered if the patient is also informed about the negative effects of the drug. Advertising something like this does not seem possible to me especially with the negative views that people have about medicine.