What’s in your sunscreen tube?

How did you choose your sunscreen?

Attractive packaging, brand-name recognition, a high sun-protection factor and affordable price account for most selections.

But it’s the active ingredients that should guide your purchase. Unfortunately, you need a magnifier to read the list and a chemistry text to understand it.

Most sunscreens prevent sunburn by blocking ultraviolet B rays, but most do not protect against harmful UVA rays. These are the rays that comprise 95 percent of the ultraviolet spectrum and contribute to skin cancer and “photoaging” that produces wrinkles, brown spots and roughened skin texture.

How can you choose a sunscreen that is effective in preventing skin cancer? Look for “broad-spectrum” on the label. The SPF number is misleading because it indicates only the amount of UVB rays blocked.

An SPF of 15 blocks 94 percent and SPF 30 blocks 97 percent. So be skeptical of the benefit of SPF 100-plus.

“Waterproof” and “sweatproof” also are misleading terms because all sunscreens need to be reapplied throughout the day and after getting wet.

The Food and Drug Administration has promised for 30 years to provide more accurate standards for sunscreens. But in the long interim, unsuspecting consumers have been slathering on a false sense of security, staying outside longer and elevating their chance of getting skin cancer.

So it’s up to you to read the fine print and scrutinize that label.

Look for the following:

■ Titanium dioxide and zinc oxide. These are very effective, mineral-based physical blockers for UVA and UVB rays. Look for 7 percent or higher concentration. Some products are engineered into nano-particles to look less white. Skin Ceuticals and Elta MD are good choices.

■ Avobenzone, or Parsol 1789. This is a chemical blocker that absorbs sunlight, breaking it down and releasing it. The product offers good UVA and UVB protection but needs a stabilizer, such as octocrylene, to prevent being broken down by the sun. Neutrogena’s Helioplex has a stabilized avobenzone.

■ Mexoryl. This is present in La Roche-Posay’s Anthelios, offering good UVA and UVB protection.

It blends well but is a bit expensive.

Ultraviolet protection factor clothing is the non-sunscreen alternative and a great option if you just hate sunscreen.

Look for UPF 60-plus from reputable companies such as SunPrecautions, Solumbra, Coolibar and Skin Savers.

Now go cruise the store aisles or websites, read labels and confidently choose a product that you will wear daily. Your skin will thank you for the investment.