When allergies make your nose stuffed up, an antihistamine generally doesn’t help. But a decongestant might.

Here’s how decongestants work: Allergies make the lining of your nose swell. Decongestants shrink swollen blood vessels and tissues. That relieves the congestion. But decongestants can’t help with sneezing or itching.

Decongestants come in pills, liquids, nose drops, and nasal sprays. Many are available without a prescription. Common decongestants include:

• Oxymetazoline (Afrin, Dristan, Vicks Sinex)
• Phenylephrine (Sudafed PE)
• Pseudoephedrine (Silfedrine, Sudafed)

Some over-the-counter decongestants — those with pseudoephedrine — are found behind the pharmacy counter.

Many medicines combine an antihistamine and decongestant, like Allegra-D, BenadrylAllergy Plus Sinus, Claritin-D, and Zyrtec-D.

Don’t use decongestant nasal sprays longer than three days. Using them longer can actually make your nose more stopped up when you stop them.

Ask your doctor before taking decongestants if you have:

• Glaucoma
• High blood pressure that’s not under control
• Heart conditions
• Thyroid problems
• Enlarged prostate
• Diabetes

Decongestants make some people feel jittery or have trouble sleeping. If that happens, cut back on caffeine while taking them. If that doesn’t help, you may need to stop taking them. Nasal sprays are less likely to cause these problems and may be a short-term solution.