Several over-the-counter supplements and products can help reduce anxiety symptoms, though they vary widely in how well they work and how long they take to kick in. The options with the strongest evidence include magnesium, ashwagandha, and certain antihistamines. None are as potent as prescription medications, but for mild to moderate anxiety, some have performed surprisingly well in clinical trials.
Before reaching for a supplement, it’s worth knowing that what works best depends on whether you’re dealing with occasional stress spikes or a persistent background hum of worry. Some OTC options act within an hour, while others need weeks of daily use before you notice a difference.
Magnesium
Magnesium is one of the most studied minerals for anxiety, and deficiency is common. Your body needs magnesium to produce serotonin, the neurotransmitter most closely tied to mood regulation. It also influences brain chemistry in ways that affect the development of both anxiety and depression. When your magnesium levels are low, your nervous system runs hotter than it should.
Magnesium glycinate is the form most often recommended for anxiety because it’s better absorbed and gentler on the stomach than cheaper forms like magnesium oxide. The general recommended daily intake is 310 to 320 mg for adult women and 400 to 420 mg for adult men, depending on age. Many people don’t hit those numbers through diet alone, especially if they eat a lot of processed food.
Magnesium is not a fast-acting fix. Most people need several weeks of consistent daily supplementation to notice a meaningful shift in their anxiety levels. One study found that short-term magnesium supplementation helped people feel less anxious after a stressful medical event, but for everyday anxiety, think of it as a slow build rather than an on-demand tool.
Ashwagandha
Ashwagandha is an herbal supplement that has gained significant traction for anxiety, and the clinical evidence behind it is more robust than for most herbs. It works primarily by lowering cortisol, your body’s main stress hormone. Multiple studies have found that ashwagandha reduces serum cortisol levels compared to placebo, and the benefits appear to be greater at doses of 500 to 600 mg per day than at lower doses.
The evidence is strong enough that an international task force created by the World Federation of Societies of Biological Psychiatry and the Canadian Network for Mood and Anxiety Treatments provisionally recommends 300 to 600 mg of ashwagandha root extract daily for generalized anxiety disorder. Look for products standardized to 5% withanolides, the active compounds. KSM-66 is a widely available standardized extract that meets this criteria.
Like magnesium, ashwagandha is a cumulative supplement. One well-designed study gave healthy adults with mild to moderate stress 500 mg daily for 60 days before measuring outcomes. You should expect to take it consistently for at least a month before judging whether it’s working for you.
Diphenhydramine and Other Antihistamines
If you need something that works right now, sedating antihistamines are your most accessible OTC option. Diphenhydramine (the active ingredient in Benadryl and many sleep aids like ZzzQuil) has a calming, sedating effect that can take the edge off acute anxiety within 30 to 60 minutes.
Its prescription cousin, hydroxyzine, is actually FDA-approved for anxiety relief and is one of the most commonly prescribed non-addictive anxiety medications. In a large randomized trial, patients with generalized anxiety disorder who took hydroxyzine did just as well as those taking a European benzodiazepine at a moderate dose. While hydroxyzine requires a prescription, diphenhydramine works through a similar antihistamine mechanism, just less precisely targeted.
The downsides are real: drowsiness, dizziness, and mental fogginess are common. This is not something you want to take before work or driving. Antihistamines are best reserved for occasional, acute anxiety rather than daily use. Your body builds tolerance to the sedating effects quickly, and long-term daily use of diphenhydramine has been linked to cognitive concerns in older adults.
CBD
CBD is widely marketed for anxiety, and lower doses in the range of 18 to 25 mg have shown positive effects on anxiety and sleep in smaller studies and case reports. However, the overall evidence base remains thin. High-quality clinical trials are still lacking, and no major medical body currently recommends CBD for psychiatric disorders.
If you try CBD, start at a low dose and give it at least a week. Quality varies enormously between products because the supplement market is loosely regulated. Look for brands that provide third-party lab testing showing exactly how much CBD is in each serving and confirming the product is free of contaminants.
Vitamin B12 and Vitamin D
These aren’t anxiety supplements in the traditional sense, but deficiencies in either vitamin can directly drive anxiety symptoms. In one study of psychiatric patients, vitamin B12 deficiency (levels below 145 pg/mL) was most prevalent among those with anxiety disorders, affecting nearly 30% of that group. Vitamin D deficiency showed a strikingly similar pattern, with about 30% of anxiety disorder patients having low levels.
If your anxiety feels disproportionate to your life circumstances, or if it came on gradually without an obvious trigger, a simple blood test can check both levels. Correcting a deficiency won’t necessarily eliminate anxiety, but it removes a biological contributor that makes everything else harder to manage. Vitamin D3 at 1,000 to 2,000 IU daily and a B12 supplement are inexpensive and widely available.
What to Avoid
The supplement aisle includes products that are genuinely dangerous. The FDA has issued warnings about tianeptine, a substance sold under brand names like Neptune’s Fix with claims that it treats anxiety and depression. Tianeptine is not approved for any medical use in the United States and is not a legal dietary ingredient. The FDA continues to receive reports of seizures, loss of consciousness, and death associated with these products. Some contain harmful ingredients not listed on the label. If you see a product promising dramatic, drug-like anxiety relief at a gas station or supplement shop, treat that as a red flag.
Kava is another supplement sometimes recommended for anxiety that carries a history of liver toxicity concerns. While some people use it without problems, the risk profile is higher than the options listed above.
Combining Approaches for Better Results
The most effective OTC strategy for most people combines a daily foundational supplement like magnesium or ashwagandha with lifestyle changes that lower your baseline anxiety level. Regular exercise, consistent sleep, and reduced caffeine intake each have evidence rivaling or exceeding most supplements.
Think of supplements as one layer in a stack. Magnesium and ashwagandha can work together safely since they operate through different mechanisms: one supports neurotransmitter production while the other lowers cortisol. Adding a B12 or vitamin D supplement makes sense if you suspect a deficiency. For those rare moments of acute anxiety, a diphenhydramine can bridge the gap, though it’s a tool for occasional use rather than a daily strategy.
Give any supplement at least four to six weeks at a consistent dose before deciding it isn’t working. Anxiety responds to sustained changes in brain chemistry, not single doses, and most of the clinical trials showing positive results ran for 60 days or longer.