Myths
Myth or fact?
Twelve claims you hear almost everywhere. Choose an answer and see right away what research and regulations say. Your result goes nowhere.
01SPF 50 protects twice as well as SPF 25.
Myth
SPF 15 blocks about 93% of UVB, SPF 30 97%, SPF 50 98%. Between 30 and 50, the difference is one per cent of what is blocked. What matters far more is how much sunscreen goes on and how often it is reapplied.
Source: Skin Cancer Foundation · 01.06.2022
02You do not need sun protection on a cloudy day.
Myth
Thin clouds barely block UV and sometimes even intensify it by scattering. Go by the UV index, not by how the sky looks.
Source: WHO: questions and answers on ultraviolet · 09.03.2016
03Hair grows back thicker and darker after shaving.
Myth
This was tested as far back as 1928, and later studies confirmed it: shaving changes neither the thickness nor the rate of growth. The blade cuts the shaft, not the bulb; the blunt end simply feels coarser.
Source: Vreeman, Carroll. BMJ 335 · 2007
04A sunbed tan prepares your skin for the beach.
Myth
A tan is the skin’s response to damage, and it protects roughly like SPF 3–4. WHO classifies sunbeds as Group 1 carcinogens: starting to use them before the age of 35 raises the risk of melanoma by 75%.
Source: IARC; IARC Working Group, International Journal of Cancer 120 · 2007–2009
05Coconut oil is a natural sunscreen.
Myth
In the test tube, oils give an SPF of up to 8, and only against UVB. Homemade sunscreens never go through testing: their protection and stability are unknown (AAD).
Source: Kaur, Saraf. Pharmacognosy Research; AAD · 2010; 02.07.2024
06Losing 50–100 hairs a day is normal.
Fact
Yes: that is how many a scalp with about 100,000 hairs normally sheds (AAD, MedlinePlus). Reasons to see a doctor: clumps, bald patches or a sudden change.
Source: AAD: Hair shedding
07Mascara should be replaced 2–4 months after opening.
Fact
That is the FDA’s advice: eye products have the shortest life because bacteria are most dangerous near the eyes. Do not thin it with water and do not share it.
Source: FDA: Shelf Life and Expiration Dating of Cosmetics · 25.02.2022
08Fingernails grow faster than toenails.
Fact
About twice as fast: 3.5 mm a month against 1.6 mm. So a fingernail grows out completely in a few months, and a toenail in about a year or longer.
Source: Yaemsiri et al. JEADV 24 · 2010
09In Moscow in December you do not need sunscreen.
Fact
In December the midday UV index in Moscow is about 0–1, and WHO advises protection from 3. The exception is mountains and snow: snow reflects up to 80% of UV, and higher up there is more of it.
Source: WHO 2002; the model on the Sun page · 2002
10A natural product is safer than a synthetic one.
Myth
Where a substance comes from does not decide how safe it is (FDA), and “natural” has no legal definition. Plant substances are frequent allergens: the EU scientific committee rates oxidised limonene and linalool from essential oils as strong ones, and lime juice in the sun leaves burns.
Source: FDA: Small Businesses & Homemade Cosmetics; SCCS/1459/11 · 18.11.2025
11Hot water opens pores and cold water closes them.
Myth
Pore size is set by sebum, the firmness of the skin around the pores and the volume of the hair follicle; water temperature is not among the causes. Hot water can irritate the skin and make pores look larger (AAD), so wash with lukewarm water.
Source: Lee S. J. et al. Dermatologic Surgery 42(3); AAD · 2016
12A hypoallergenic product does not cause allergies.
Myth
The word “hypoallergenic” has no binding standard: in the US a court struck down a 1975 rule, and the manufacturer decides for itself. British dermatologists checked 208 such products and found a known allergen in 79 (38%).
Source: FDA: Hypoallergenic cosmetics; BAD · 2023