Disclosure: Dynamo Delay makes a competing lidocaine delay spray. We have not tested Stud 100, and we received nothing from its maker. Every product fact below comes from that product's drug facts label on DailyMed, the U.S. National Library of Medicine's label database, or the manufacturer's FAQ where noted, so you can check each one yourself.
Stud 100 is one of the best-known delay sprays. People searching for it usually want the basics: what's in it, how to use it, how long it takes, and whether it's safe for them and their partner. This Stud 100 review answers those questions using the official label on DailyMed and the manufacturer's FAQ.
What Is Stud 100?
Stud 100 is a topical anesthetic spray for premature ejaculation, sold without a prescription. DailyMed lists its U.S. label, filed by Pound International Corp, as an "OTC Monograph Drug" (monograph ID M017); the manufacturer describes this as the FDA monograph for male genital desensitizers.1,2 The manufacturer also says it has been on the market since 1970, is sold in pharmacies, adult stores and online, and is regulated by the UK's MHRA.2
The label states its use as: "temporarily reduces sensitivity of the penis, which helps to delay ejaculation in cases of over-rapid or premature ejaculation."1
Ingredients and Dose per Spray
- Active ingredient: lidocaine base 9.6% w/w, approximately 10 mg per spray.1
- Inactive ingredients: fragrance, isopropyl myristate, solvent (listed in the product data as 2-(2-ethylhexyloxy)ethanol), and stearic acid.1
- Size: 7/16 fl oz can (12.5 mL in the label's product data) with a metered pump.1 The manufacturer says each can holds about 120 sprays.2
Lidocaine is a local anesthetic. It temporarily blocks nerve signals in the skin, which reduces how strongly touch is felt. Guidelines from the International Society for Sexual Medicine report strong evidence for topical anesthetics as a treatment for lifelong premature ejaculation.3
How to Use Stud 100
Per the label and the manufacturer's FAQ:1,2
- Start with 3 sprays to the head and shaft of the penis.
- Don't exceed 10 sprays per application or 24 sprays in 24 hours. Use the minimum amount that works for you.
- Wait 5 to 15 minutes so the product can absorb (the manufacturer says this also helps prevent transfer to your partner).
- Wash the product off after intercourse.
- Keep it away from your eyes and don't inhale it.
The manufacturer recommends waiting 5 to 15 minutes after spraying.2 On duration, its FAQ says only that how long the effect lasts "varies between individuals" and depends on the amount used and timing.2 We haven't found a published duration figure on the official label or FAQ, so we don't quote one.
Partner Transfer, Oral Sex and Condoms
- Transfer: the manufacturer says the wait time helps prevent transfer to a partner.2 The ISSM guidelines note that some topical anesthetics can transfer and cause partner numbness unless a condom is used.3
- Oral sex: per the FAQ, the spray may transfer to a partner's mouth and cause temporary numbness of the lips and tongue. Check that your partner isn't allergic to lidocaine first.2
- Condoms: the manufacturer says studies with all condom types haven't been done and it can't comment on effects on condom material or efficacy.2
- Pregnancy: the label says not to use it if your partner is pregnant.1 The FAQ adds that it shouldn't be used if you're trying to conceive.2
Side Effects and Who Shouldn't Use It
Possible side effects listed by the manufacturer: temporary numbness or tingling, mild burning or stinging, skin irritation, and rare allergic reactions.2
Don't use it, per the label,1 if you or your partner are allergic to local anesthetics, the skin is broken or inflamed, or your partner is pregnant. Ask a doctor first if you have, or ever had, liver or kidney problems, or if you take prescription drugs.1 Stop and see a doctor if you or your partner get a rash, burning or itching, or if you feel unwell after using it.1
See also our general guide to delay spray side effects.
Stud 100 vs. Dynamo Delay: Label Facts Side by Side
Because we make a competing spray, we've limited this section to facts printed on each product's DailyMed label or stated by its maker, without rating either one. We haven't run head-to-head tests and make no claim that either works better or lasts longer.
| Stud 100 | Dynamo Delay Spray | |
|---|---|---|
| Active ingredient | Lidocaine base 9.6% w/w1 | Lidocaine USP 13%4 |
| Lidocaine per spray (label) | About 10 mg1 | About 10 mg4 |
| Directions | 3 or more sprays, not more than 10, to head and shaft; max 24 in 24 hours; wash off after1 | 3 or more sprays, not to exceed 10, to head and shaft before intercourse; wash off after4 |
| Inactive ingredients listed | Fragrance, isopropyl myristate, solvent, stearic acid1 | Isopropyl palmitate, SD alcohol 40B, stearic acid4 |
| Size / sprays per container | 7/16 fl oz (12.5 mL); about 120 sprays (maker FAQ)1,2 | 3/4 fl oz (22.2 mL), 270+ sprays4 |
| Condoms | Maker says it has not studied all condom types2 | Not addressed on label4 |
Does "13% vs 9.6%" mean one is stronger?
No. The percentage is concentration: how much lidocaine is in the liquid. What reaches your skin depends on how much liquid each pump delivers. Both labels state about 10 mg of lidocaine per spray,1,4 so the dose per spray is the same. Your total dose is set by how many sprays you use, not by the percentage on the box.
- Inactive ingredients. Stud 100's label lists fragrance; Dynamo's label lists isopropyl palmitate, SD alcohol 40B and stearic acid.1,4 If you react to fragrances, compare the lists.
- Warnings panel. Stud 100's label lists more specific warnings (anesthetic allergy, partner pregnancy, liver or kidney problems, broken skin, a 24-sprays-per-day limit).1 Those cautions are sensible with any lidocaine product, whichever brand you buy.
Whichever you choose, read and follow its current label. Dynamo Delay Spray is another lidocaine option. For a broader look at the category, see our best delay spray 2026 label comparison. Delay sprays can be used alongside techniques like stop-start; see how to stop premature ejaculation.
When to See a Doctor
Stud 100's label says to stop and consult a doctor if the product, used as directed, doesn't provide relief, because premature ejaculation may be due to a condition requiring medical supervision.1 Also see a doctor if you almost always ejaculate within about a minute and it causes distress; if the problem started suddenly, or comes with erection problems, pain or blood in your semen; or if you or your partner develop a rash, burning, itching or any reaction.
The Bottom Line
Stud 100 is a long-established OTC lidocaine spray: 9.6% lidocaine, about 10 mg per spray, 3 to 10 sprays per use (no more than 24 in 24 hours), washed off after sex. Its label lists fragrance, and the maker says it hasn't studied all condom types. Read the full label, start with the smallest dose that works, and talk to a doctor if delay sprays don't help or premature ejaculation is affecting your life.
This article was drafted with AI editorial assistance and reviewed for accuracy before publication.
